PID-based Refrigeration Machine Frequency Converter Optimization Control Method and System

Abstract

The present invention relates to the field of adaptive control systems, and proposes a PID-based refrigerator inverter optimization control method and system, including: collecting temperature data of different positions in the refrigeration system and pressure data of each position, and obtaining ambient temperature data; obtaining several cycles of each position; obtaining the initial heat accumulation factor of each cycle of the exhaust pipe position of each position; obtaining the temperature hysteresis factor of each position, adjusting and obtaining the cycle heat accumulation factor of the exhaust pipe position of each position; obtaining the temperature transfer factor between different positions, combining the initial heat accumulation factor and the cycle heat accumulation factor, and obtaining the heat accumulation deviation of the exhaust pipe position of each position; obtaining the final heat accumulation degree of each position in each cycle; adjusting the PID control parameters according to the final heat accumulation degree of each position in each cycle, and realizing the optimization control of the refrigerator inverter. The present invention aims to solve the problem that the residual heat in the system affects the inverter regulation control during the refrigerator inverter cycle.

Description

Technical Field

[0001] The present invention relates to the field of adaptive control systems, and in particular to a PID-based refrigerator inverter optimization control method and system. Background Art

[0002] A refrigerator inverter is an electrical device used to adjust the speed of the compressor of refrigeration equipment (such as air conditioners, refrigerators, etc.); it controls the operating speed of the compressor by changing the frequency supplied to the motor, thereby achieving precise control of the refrigeration effect; it is widely used in household air conditioning, commercial refrigeration, industrial refrigeration and other fields. By optimizing the operating state, the inverter can significantly reduce the energy consumption of the refrigerator, improve the energy utilization efficiency of the refrigeration system, and can more accurately control the refrigeration temperature, improve comfort, effectively improve the energy efficiency of the refrigeration system, and greatly improve the user experience.

[0003] During the refrigeration cycle, the refrigerant enters from the compressor suction port and completes a cycle through the compressor, condenser, capillary tube, evaporator and return air pipe. In the compressor, condenser and evaporator, the refrigerant participates in heat exchange multiple times through compression, heat dissipation and vaporization processes. During multiple cycles, there is a heat accumulation effect that affects the heat exchange efficiency of subsequent cycles. At the same time, the temperature of the cycle is affected by changes in the external environment. It is necessary to quantify the heat accumulation effect and external environmental changes so that the corresponding load changes can be compensated by adjusting the PID parameters during the inverter adjustment of the compressor. Summary of the invention

[0004] The present invention provides a PID-based refrigerator inverter optimization control method and system to solve the problem that the residual heat in the system affects the inverter regulation control during the existing refrigerator inverter cycle. The technical solution adopted is as follows:

[0005] The present invention proposes a PID-based refrigerator inverter optimization control method, which includes the following steps:

[0006] Collect temperature data and pressure data of different parts of the refrigeration system, and obtain ambient temperature data;

[0007] According to the time series change of the temperature data at the same position, several cycles of each position are obtained; according to the temperature change in each cycle at the same position, the initial heat accumulation factor of each cycle of the exhaust pipe position at each part is obtained; according to the correlation between the temperature data changes at different positions of the same part, the temperature hysteresis factor of each part is obtained, and the cycle heat accumulation factor of the exhaust pipe position at each part is obtained by adjustment;

[0008] According to the correlation between the temperature data changes between the connection positions of different parts and the changes in the ambient temperature data, the temperature transfer factor between different parts is obtained, and the heat accumulation deviation of the exhaust pipe position of each part is obtained by combining the initial heat accumulation factor and the cycle heat accumulation factor; based on the changes in the pressure data of the same part in different cycles, the standard pressure sequence of each part is obtained, and the pressure changes of each part in each cycle are predicted based on the standard pressure sequence, and the final heat accumulation degree of each part in each cycle is obtained by combining the heat accumulation deviation of the exhaust pipe position of each part;

[0009] According to the final heat accumulation degree of each part in each cycle, the PID control parameters are adjusted to achieve optimal control of the refrigerator inverter.

[0010] Optionally, the method of obtaining a number of cycles at each position includes:

[0011] All temperature data collected at any position are used to form a temperature data sequence of the position in chronological order, and several maximum values ​​in the temperature data sequence are obtained by using the AMPD algorithm; a coordinate system is constructed with time as the horizontal axis and temperature as the vertical axis to obtain a temperature data curve corresponding to the temperature data sequence, a symmetric temperature curve is obtained by symmetrically treating the temperature data curve about the horizontal axis, and several maximum values ​​are obtained by using the AMPD algorithm for the symmetric temperature curve, and the corresponding time of the maximum value of the symmetric temperature curve is the corresponding time of several minimum values ​​in the temperature data sequence, thereby obtaining several minimum values ​​of the temperature data sequence;

[0012] Calculate the mean of all temperature data in the temperature data sequence as the amplitude mean of the temperature data sequence; respectively obtain the maximum mean and minimum mean of the temperature data sequence, and calculate the absolute value of the difference with the amplitude mean, and use the extreme point type with the largest difference from the amplitude mean as the basis for period division;

[0013] For the maximum value as the basis for period division, the first temperature data and all the maximum values ​​in the temperature data sequence are used as segmentation points, and the temperature data sequence is divided into several data segments through the segmentation points, and each data segment is used as a cycle.

[0014] Optionally, the initial heat accumulation factor of each cycle of the exhaust pipe position of each part is obtained by:

[0015] For one cycle of the temperature data sequence at any exhaust pipe position, Initial heat accumulation factor of the second cycle The calculation method is:

[0016]

[0017] in, Indicates The first temperature data in the cycle, Indicates The last temperature data in the cycle, and Respectively represent Second cycle and The temperature data corresponding to the extreme point that is not the first temperature data in the cycle.

[0018] Optionally, the specific method of obtaining the temperature hysteresis factor of each part includes:

[0019] Get the position of the air inlet of the condenser The time period corresponding to the first cycle is used to obtain the temperature data segment corresponding to the time period of the exhaust pipe position of the condenser, and this is used as the first temperature data segment of the air inlet position of the condenser. The control temperature sequence of the first cycle; The Pearson correlation coefficient is obtained between the first cycle and its control temperature sequence. The length of the first cycle remains unchanged and the temperature data is gradually moved backward in steps to obtain the first The moving temperature sequence of each movement in the first cycle is calculated, and the Pearson correlation coefficient between the moving temperature sequence of each movement and the control temperature sequence is calculated. The maximum value of the correlation coefficient corresponds to the step length of the first movement as the first step length of the air inlet position of the condenser. The hysteresis duration of the sub-cycle;

[0020] The hysteresis duration of each cycle at the air inlet position of the condenser is obtained, and the ratio of the mean of all hysteresis durations to the quantitative mean of the temperature data of each cycle at the air inlet position of the condenser is taken as the temperature hysteresis factor of the condenser.

[0021] Optionally, the cyclic heat accumulation factor of the exhaust pipe position at each part is obtained by:

[0022]

[0023] in, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the temperature hysteresis factor of the condenser part, Indicates the exhaust pipe position of the condenser Initial heat accumulation factor of the sub-cycle;

[0024] Obtain the cycle heat accumulation factor of each cycle at the exhaust pipe position of the evaporator.

[0025] Optionally, the temperature transfer factor between different parts is obtained by:

[0026] Get the exhaust pipe position of the compressor The time period corresponding to the first cycle is used to obtain the temperature data segment of the corresponding time period of the air inlet position of the condenser, and the temperature data segment of the exhaust pipe position of the compressor is obtained. The hysteresis duration of the sub-cycle;

[0027] According to the position of the exhaust pipe of the compressor The hysteresis time of the first cycle is to place the exhaust pipe at the compressor position The time obtained by adding the hysteresis time to the time corresponding to any temperature data in the second cycle, and the temperature data corresponding to the air inlet position of the condenser is used as the transfer temperature data of the temperature data, and the difference between the temperature data and the transfer temperature data is calculated as the temperature transfer amount of the temperature data; the temperature data corresponding to the exhaust pipe position of the compressor is used as the temperature data corresponding to the air inlet position of the condenser. The average value of the temperature transfer of all temperature data in the cycle is taken as the value of the temperature transfer of the exhaust pipe at the compressor. Temperature transfer parameters of the secondary cycle;

[0028] Combined with the ambient temperature data, the temperature transfer factor of the compressor to the condenser The calculation method is:

[0029]

[0030] in, Indicates the number of cycles at the exhaust pipe position of the compressor. Indicates the position of the exhaust pipe at the compressor. The temperature transfer parameter of the cycle, Indicates the position of the exhaust pipe at the compressor. The first temperature data of the cycle, Indicates the position of the exhaust pipe at the compressor. The mean value of all ambient temperature data in the time period corresponding to the cycle;

[0031] Get the temperature transfer factor of the condenser section to the evaporator section.

[0032] Optionally, the heat accumulation deviation of the exhaust pipe position at each location is obtained, including the specific method of:

[0033]

[0034] in, Indicates the exhaust pipe position of the condenser The heat accumulation deviation of the cycle, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the position of the exhaust pipe at the compressor. The initial heat accumulation factor of the cycle, Indicates the temperature transfer factor of the compressor part to the condenser part;

[0035] Obtain the heat accumulation deviation of each cycle at the exhaust pipe position of the evaporator.

[0036] Optionally, the standard pressure sequence of each part is obtained by:

[0037] The pressure data of the condenser part are arranged in chronological order to form a pressure data sequence of the condenser part. Based on the cyclic division of the temperature data sequence of the exhaust pipe position of the condenser part, the pressure data sequence is cyclically divided according to the corresponding time to obtain the pressure data segments of each cycle of the condenser part. The DTW distances between the pressure data segments of all cycles are calculated pairwise, and the pressure data segment with the smallest mean DTW distance between other pressure data segments is used as the standard pressure sequence of the condenser part.

[0038] Optionally, the method of obtaining the final heat accumulation degree of each part in each cycle includes:

[0039] The standard pressure series is fitted by the least square method to obtain the fitting function. For the pressure data segment of the next cycle, all the pressure data except the last one are input into the fitting function to output the pressure prediction value corresponding to the last pressure data; The final heat accumulation of the cycle The calculation method is:

[0040]

[0041] in, Indicates the exhaust pipe position of the condenser The heat accumulation deviation of the cycle, Indicates the condenser part The last pressure data of the cycle, Indicates the condenser part The pressure prediction value corresponding to the last pressure data of the next cycle, is the effect of pressure change on temperature change.

[0042] The present invention also proposes a PID-based refrigerator inverter optimization control system, which includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of the above method are implemented.

[0043] The beneficial effects of the present invention are as follows: the present invention analyzes the temperature and pressure of each part of the refrigeration system where the refrigerator inverter is located, quantifies the accumulated heat of each part in each cycle, and analyzes the corresponding temperature, so as to adjust the PID control parameters of the refrigerator inverter; wherein the temperature data of each position is segmented based on the change in time series to obtain several cycles, each cycle reflects a temperature change process at the same position, and according to the temperature change of adjacent cycles and the processing time of the corresponding part, the time lag of the temperature of the corresponding part is quantified, so as to accumulate the heat accumulation of the current cycle and the previous cycle, and quantify the accumulated heat under each cycle; by analyzing the temperature of the parts The time series correlation of the temperature data changes between the two parts is analyzed to quantify the temperature transfer factor, and the heat accumulation factor is adjusted to obtain the heat accumulation deviation. On the basis of the heat accumulation of the internal circulation of each part, the heat accumulation brought by the previous part is adjusted; then the changes in the internal pressure of each part are analyzed, and the difference between the pressure change trend of each cycle and that under normal conditions is analyzed to quantify the degree of pressure change and the impact of the temperature change in the corresponding part to obtain the final heat accumulation degree; the temperature deviation analysis is performed based on the final heat accumulation degree, which can compensate for the load caused by the heat accumulation effect, thereby optimizing the control of the refrigerator inverter and ensuring that the temperature control meets the standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0045] Figure 1 A schematic flow chart of a PID-based refrigerator inverter optimization control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] See also Figure 1 , which shows a flow chart of a PID-based refrigerator inverter optimization control method provided by an embodiment of the present invention, the method comprising the following steps:

[0048] Step S001: Collect temperature data of various positions in the refrigeration system and pressure data of various positions, and obtain ambient temperature data.

[0049] The purpose of this embodiment is to analyze the heat accumulated in the refrigeration system where the refrigerator inverter is located during the refrigerant circulation process, so as to quantify the influence of the heat accumulation effect of different parts in the refrigeration system under multiple cycles on the refrigerant heat exchange efficiency, so as to adjust the refrigerator inverter and compensate for the corresponding load changes, thereby realizing the optimal control of the refrigerator inverter.

[0050] Specifically, pressure sensors are arranged in the compressor, condenser and evaporator in the refrigeration system to collect pressure data of each part; temperature sensors are arranged at the exhaust pipe position of each part, as well as the air intake position of the condenser and the evaporator, to collect temperature data of different parts; after the refrigeration system starts to run, the collection time interval is set according to the duration of a single refrigeration cycle, and the sampling interval of this embodiment is set to 1 second; at the same time, the room temperature is measured by a temperature sensor arranged outside the refrigeration system, and the collected room temperature is used as the ambient temperature data, and the sampling time interval is also 1 second.

[0051] Step S002, according to the time series change of the temperature data at the same position, obtain several cycles of each position; according to the temperature change in each cycle at the same position, obtain the initial heat accumulation factor of each cycle of the exhaust pipe position of each part; according to the correlation between the temperature data changes at different positions of the same part, obtain the temperature hysteresis factor of each part, and adjust and obtain the cycle heat accumulation factor of the exhaust pipe position of each part.

[0052] It should be noted that during the refrigeration cycle, the refrigerant needs to pass through the compressor, condenser, evaporator and other parts. The temperature of the refrigerant will change as it undergoes compression, heat dissipation and vaporization in each part. The temperature of the gas in the same part will show periodic changes. One cycle is a temperature change cycle process in that part. The temperature data sequence of each part needs to be segmented by period division to obtain each cycle. In a cycle at the same position, for the exhaust pipe position of each part, the cycle is a process from the temperature of the gas discharge to the normal temperature and then to the temperature of the gas discharge. Based on this change, the residual heat in each position in the cycle can be quantified.

[0053] Preferably, in one embodiment of the present invention, a number of cycles at each position are obtained according to the time series change of the temperature data at the same position, and the specific method includes:

[0054] It should be noted that in the temperature data sequences at different positions, since the temperature change process at each position is different, that is, in a single cycle at different positions, the normal temperature may be a peak value or a valley value, it is necessary to analyze the difference between the temperature through which the gas passes and the normal temperature to determine how to divide the period, that is, the cycle. The normal temperature corresponds to most of the time in the cycle, which is represented by calculating the amplitude mean of the temperature data sequence, and the temperature of the gas discharge may be higher or lower than the normal temperature, but compared with the amplitude mean, its deviation will be much greater than the deviation of the normal temperature from the amplitude mean, so the basis for period division at each position is obtained, and the cycle division is completed.

[0055] Specifically, all temperature data collected at any position are used to form a temperature data sequence at that position in chronological order, and several maximum values ​​in the temperature data sequence are obtained through the AMPD (automatic multi-scale peak search) algorithm; a coordinate system is constructed with time as the horizontal axis and temperature as the vertical axis to obtain a temperature data curve corresponding to the temperature data sequence, and a symmetric temperature curve is obtained by symmetrically obtaining the temperature data curve about the horizontal axis, and several maximum values ​​are obtained from the symmetric temperature curve through the AMPD algorithm, and the corresponding time of the maximum value of the symmetric temperature curve is the corresponding time of several minimum values ​​in the temperature data sequence, thereby obtaining several minimum values ​​of the temperature data sequence; wherein the AMPD algorithm is a well-known technology and will not be repeated in this embodiment.

[0056] Furthermore, the mean of all temperature data in the temperature data sequence is calculated as the amplitude mean of the temperature data sequence; the maximum mean and minimum mean of the temperature data sequence are respectively obtained, and the absolute value (difference) of the difference with the amplitude mean is respectively calculated, and the type of extreme point with the largest difference from the amplitude mean is used as the basis for period division; taking the maximum value as the basis for period division as an example, the first temperature data and all maximum values ​​in the temperature data sequence are used as segmentation points, and the temperature data sequence is divided into several data segments through the segmentation points, each data segment is used as a cycle, and the segmentation points are the first temperature data in each cycle.

[0057] Preferably, in one embodiment of the present invention, the initial heat accumulation factor of each cycle of the exhaust pipe position at each part is obtained according to the temperature change in each cycle at the same position, and the specific method includes:

[0058] For one cycle of the temperature data sequence at any exhaust pipe position, Initial heat accumulation factor of the second cycle The calculation method is:

[0059]

[0060] in, Indicates The first temperature data in the cycle (the starting extreme value), Indicates The last temperature data in the next cycle (the temperature data before the extreme value at the beginning of the next cycle), and Respectively represent Second cycle and The temperature data corresponding to the extreme point that is not the first temperature data in the secondary cycle, that is, the temperature data corresponding to the extreme point of the extreme point type that is not the basis for period division in the cycle.

[0061] It should be noted that the temperature change at the exhaust pipe position can reflect the temperature accumulation in the corresponding part during two adjacent cycles, with the difference between the first and last temperature data of the exhaust pipe as a benchmark. At the same time, the smaller the difference between the normal temperature restored at the exhaust pipe position and the extreme value, and the smaller it is compared with the previous cycle, it indicates that the temperature accumulation of the corresponding part in the two cycles is greater, that is, the residual temperature of the previous cycle has not been eliminated, and it is necessary to increase the extreme value difference to reflect the initial heat accumulation factor.

[0062] Preferably, in one embodiment of the present invention, based on the correlation between the temperature data changes at different positions of the same part, the temperature hysteresis factor of each part is obtained, and the cycle heat accumulation factor of the exhaust pipe position of each part is adjusted and obtained, and the specific method includes:

[0063] It should be noted that in the same part, due to the temperature change process of the refrigerant in the part, there is a correlation between the temperature data changes at the intake port position and the exhaust pipe position in the same part, but this correlation will have a time lag. The length of the lag is the length of the refrigerant treatment process in the corresponding part. The length of the lag is used as the weight of the accumulated heat in the previous cycle, so as to adjust the initial heat accumulation factor to obtain the cycle heat accumulation factor, that is, the duration of the influence of the accumulated heat of the previous cycle on the current cycle.

[0064] Specifically, taking the condenser as an example, the first The time period corresponding to the first cycle is used to obtain the temperature data segment corresponding to the time period of the exhaust pipe position of the condenser, and this is used as the first temperature data segment of the air inlet position of the condenser. The control temperature sequence of the first cycle; The Pearson correlation coefficient is obtained between the cycle and its control temperature sequence, with a step size of 1 and a maximum step size of The number of temperature data in the cycle, The length of the first cycle remains unchanged and the temperature data is gradually moved backward in steps to obtain the first The moving temperature sequence of each movement in the first cycle is calculated, and the Pearson correlation coefficient between the moving temperature sequence of each movement and the control temperature sequence is calculated. The maximum value of the correlation coefficient corresponds to the step length of the first movement as the first step length of the air inlet position of the condenser. The hysteresis duration of the sub-cycle.

[0065] Furthermore, the hysteresis time of each cycle of the air inlet position of the condenser is obtained, and the ratio of the mean of all hysteresis time and the quantitative mean of the temperature data of each cycle of the air inlet position of the condenser is used as the temperature hysteresis factor of the condenser; then the temperature hysteresis factor of the exhaust pipe position of the condenser is calculated. Cycle heat accumulation factor of the sub-cycle The calculation method is:

[0066]

[0067] in, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the temperature hysteresis factor of the condenser part, Indicates the exhaust pipe position of the condenser The initial heat accumulation factor of the cycle; in particular, when That is, in the first cycle, the initial heat accumulation factor of the first cycle at the exhaust pipe position of the condenser is directly used as the cycle heat accumulation factor of the first cycle at the corresponding position.

[0068] Similarly, for the evaporator part, based on the correlation between the time series changes of the temperature data at the air intake position and the exhaust pipe position of the evaporator part, the temperature hysteresis factor of the evaporator part is obtained, and combined with the initial heat accumulation factor of each cycle of the exhaust pipe position of the evaporator part, the cyclic heat accumulation factor of each cycle of the exhaust pipe position of the evaporator part is obtained.

[0069] It should be noted that the initial heat accumulation factor reflects the accumulation of heat in the current cycle. For multiple cycles, the heat will gradually accumulate, and the initial heat accumulation factor needs to be corrected based on the heat accumulated in the previous cycle. In the same part, the treatment process of the refrigerant once can reflect the timing change correlation between the suction port position and the exhaust pipe position. This lag effect can reflect the time lag degree of the heat accumulated in the previous cycle, that is, after the lag time has passed, the temperature change corresponding to the exhaust pipe position can independently reflect the heat accumulation of the current cycle, and it is necessary to use this to obtain the accumulated heat at the exhaust pipe position.

[0070] At this point, by segmenting the temperature data of each position based on the changes in time series, several cycles are obtained. Each cycle reflects a temperature change process at the same position. According to the temperature changes of adjacent cycles and the processing time of the corresponding parts, the time lag of the temperature of the corresponding parts is quantified. In this way, the heat accumulation of the current cycle and the previous cycles is accumulated, and the accumulated heat in each cycle is quantified.

[0071] Step S003, according to the correlation between the temperature data changes between the connection positions of different parts and the changes in the ambient temperature data, the temperature transfer factor between different parts is obtained, and the heat accumulation deviation of the exhaust pipe position of each part is obtained by combining the initial heat accumulation factor and the cycle heat accumulation factor; based on the changes in the pressure data of the same part in different cycles, the standard pressure sequence of each part is obtained, and the pressure changes of each part in each cycle are predicted based on the standard pressure sequence, and the final heat accumulation degree of each part in each cycle is obtained by combining the heat accumulation deviation of the exhaust pipe position of each part.

[0072] It should be noted that during each cycle of each part, changes in ambient temperature will affect the temperature changes of the gas during the cycle and the temperature of each position. Therefore, the heat accumulation effect of each part needs to be adjusted by considering the impact of environmental changes; and for the condenser and evaporator parts, the two parts reduce the temperature through heat dissipation and vaporization processes respectively. In the process of heat residue, the two parts will be affected not only by the residual influence of the previous cycle, but also by the temperature change of the previous part. Therefore, the temperature deviation caused by this needs to adjust the inverter for load compensation to obtain the heat accumulation deviation of each part.

[0073] Preferably, in one embodiment of the present invention, the temperature transfer factor between different parts is obtained according to the correlation between the temperature data changes between the connection positions of different parts and the changes in the ambient temperature data, and the heat accumulation deviation of the exhaust pipe position of each part is obtained by combining the initial heat accumulation factor and the cycle heat accumulation factor, including the specific method of:

[0074] It should be noted that after the gas flows out from the exhaust pipe position of the compressor, it is directly connected to the condenser position. The gas in this position is high-temperature and high-pressure gas (gas-liquid mixture). In the process of reaching the suction pipe position of the condenser, it will be affected by the room temperature and reduce some heat. It is necessary to quantify the impact of the ambient temperature data based on the difference between the ambient temperature data and the temperature data of the exhaust pipe position, combined with the lag effect caused by the length of time the gas flows, and use this to adjust the temperature impact brought by the previous position, and then obtain the temperature deviation of the exhaust pipe position of each part.

[0075] Specifically, obtain the exhaust pipe position of the compressor. The time period corresponding to the first cycle is used to obtain the temperature data segment of the time period corresponding to the suction port position of the condenser, and the temperature data segment of the exhaust pipe position of the compressor is obtained according to the above-mentioned method for obtaining the hysteresis time length. The hysteresis time of the cycle; according to the position of the exhaust pipe of the compressor The hysteresis time of the first cycle is to place the exhaust pipe at the compressor position The time obtained by adding the hysteresis time to the time corresponding to any temperature data in the second cycle, and the temperature data corresponding to the air inlet position of the condenser is used as the transfer temperature data of the temperature data, and the difference between the temperature data and the transfer temperature data is calculated as the temperature transfer amount of the temperature data; the temperature data corresponding to the exhaust pipe position of the compressor is used as the temperature data corresponding to the air inlet position of the condenser. The average value of the temperature transfer of all temperature data in the cycle is taken as the value of the temperature transfer of the exhaust pipe at the compressor. The temperature transfer parameters of the sub-cycle; combined with the ambient temperature data, the temperature transfer factor of the compressor part to the condenser part The calculation method is:

[0076]

[0077] in, Indicates the number of cycles at the exhaust pipe position of the compressor. Indicates the position of the exhaust pipe at the compressor. The temperature transfer parameter of the cycle, Indicates the position of the exhaust pipe at the compressor. The first temperature data of the cycle, Indicates the position of the exhaust pipe at the compressor. The average of all ambient temperature data in the time period corresponding to the cycle; it should be noted that in the calculation process of each cycle, if the temperature data of the exhaust pipe position of the compressor part is in the last cycle ending at the current moment, and the temperature data cannot be obtained at the suction port position of the condenser part, that is, the gas does not flow to the corresponding position in sequence, then the last cycle will not participate in the above calculation.

[0078] Similarly, the exhaust pipe position of the condenser part and the air intake position of the evaporator part are connected by a capillary tube. Based on the temperature data of the exhaust pipe position of the condenser part and the temperature data of the air intake position of the evaporator part, the temperature transfer factor of the condenser part to the evaporator part is obtained according to the above method.

[0079] It should be noted that the temperature transfer parameter reflects the heat accumulated in the previous part when the gas is transferred from the exhaust pipe position of the previous part to the air intake position of the current part. During the transfer process, the gas will lose (high temperature and high pressure) part of the heat or absorb (low temperature and high pressure) part of the heat under the influence of the ambient temperature. The temperature transfer parameter is corrected in combination with the environmental data to obtain the temperature transfer factor between the parts.

[0080] Furthermore, the exhaust pipe position of the condenser is Heat accumulation deviation of each cycle The calculation method is:

[0081]

[0082] in, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the position of the exhaust pipe at the compressor. The initial heat accumulation factor of the cycle, Indicates the temperature transfer factor from the compressor to the condenser.

[0083] Similarly, for the evaporator part, based on the difference between the cyclic heat accumulation factor of each cycle at the exhaust pipe position of the condenser part and the temperature transfer factor of the condenser part to the evaporator part, the cyclic heat accumulation factor of each cycle at the exhaust pipe position of the evaporator part is adjusted to obtain the heat accumulation deviation of each cycle at the exhaust pipe position of the evaporator part.

[0084] It should be noted that by correcting the initial heat accumulation factor of the previous part through the temperature transfer factor, the heat transferred from the previous part to the current part is obtained. On this basis, combined with the circulating heat accumulation factor, the heat accumulation at the exhaust pipe position of the current part takes into account the heat accumulation of the internal circulation of the part and the heat accumulation generated by the previous part.

[0085] Preferably, in one embodiment of the present invention, based on the change of pressure data in different cycles of the same part, a standard pressure sequence of each part is obtained, and the pressure change of each part in each cycle is predicted based on the standard pressure sequence, and combined with the heat accumulation deviation of the exhaust pipe position of each part, the final heat accumulation degree of each part in each cycle is obtained, including the specific method of:

[0086] It should be noted that the frequency converter needs to adjust the frequency based on the temperature deviation in the condenser and the evaporator. The condenser is a heat dissipation process and the pressure will not change. The evaporator is a vaporization process and the pressure will change. The heat accumulation deviation needs to be further corrected based on the pressure change to quantify the heat accumulation degree in the condenser and evaporator parts. Under closed conditions, changes in pressure will cause changes in temperature. The standard pressure sequence is obtained by measuring the pressure in each cycle of the same part. The standard pressure sequence reflects the pressure change trend of the corresponding part during a single treatment process. The pressure change of each cycle is determined by a fixed change trend to quantify the temperature change, thereby correcting the heat accumulation deviation to obtain the final heat accumulation degree.

[0087] Specifically, taking the condenser part as an example, the pressure data of the condenser part is organized into a pressure data sequence of the condenser part in chronological order, and the pressure data sequence is cyclically divided based on the temperature data sequence of the exhaust pipe position of the condenser part according to the corresponding time to obtain the pressure data segments of each cycle of the condenser part, and the DTW distances are calculated between the pressure data segments of all cycles, and the pressure data segment with the smallest mean DTW distance with other pressure data segments is used as the standard pressure sequence of the condenser part.

[0088] Further, the standard pressure sequence is fitted by the least square method to obtain a fitting function, wherein the least square method for fitting the sequence to obtain the fitting function is an existing method and will not be described in detail in this embodiment; For the pressure data segment of the next cycle, all the pressure data except the last one are input into the fitting function to output the pressure prediction value corresponding to the last pressure data; then the pressure data of the condenser part The final heat accumulation of the cycle The calculation method is:

[0089]

[0090] in, Indicates the exhaust pipe position of the condenser The heat accumulation deviation of the cycle, Indicates the condenser part The last pressure data of the cycle, Indicates the condenser part The pressure prediction value corresponding to the last pressure data of the next cycle, It is the influence function of pressure change on temperature change, that is, the influence function of input pressure change value and output temperature change value.

[0091] Similarly, the pressure data changes of the evaporator are analyzed, and the pressure prediction value is obtained for the last pressure data of each cycle, thereby obtaining the final heat accumulation degree of each cycle in the evaporator; for the compressor part, on the basis of the initial heat accumulation factor of each cycle (corresponding to the heat accumulation deviation of the exhaust pipe position of each part in the above formula), the final heat accumulation degree of each cycle in the compressor part is obtained through the last pressure data of each cycle and its prediction value.

[0092] It should be noted that the standard pressure sequence is used as a benchmark, and then the pressure prediction value is obtained for the last pressure data of each cycle. The greater the deviation from the pressure prediction value, the greater the difference between the pressure change in the cycle and the normal change trend, and the greater the impact on the temperature. The heat accumulation deviation is then adjusted to obtain the final heat accumulation degree.

[0093] At this point, the temperature transfer factor is quantified by analyzing the time-series correlation of the temperature data changes between parts, and the heat accumulation factor is adjusted to obtain the heat accumulation deviation. On the basis of the heat accumulation of the internal circulation of each part, adjustments are made through the heat accumulation brought by the previous part; then the changes in the internal pressure of each part are analyzed, and by analyzing the difference between the pressure change trends of each cycle and those under normal conditions, the degree of pressure change and the impact of the temperature change in the corresponding part are quantified to obtain the final degree of heat accumulation.

[0094] Step S004: adjust the PID control parameters according to the final heat accumulation degree of each part in each cycle to achieve optimal control of the refrigerator inverter.

[0095] It should be noted that for the final heat accumulation degree of each part in each cycle, a positive value indicates that the temperature of each part has increased compared to the corresponding normal temperature, and it is necessary to increase the inverter load to reduce the temperature, so as to output the PID control parameters; a negative value indicates that the temperature of each part is lower than the corresponding normal temperature, which may be caused by pressure changes or excessive inverter power. It is necessary to reduce the inverter load and output the PID control parameters based on the original temperature adjustment of the inverter power.

[0096] Specifically, for the most recent cycle of each part before the current moment, it corresponds to a final heat accumulation degree. The final heat accumulation degree of the most recent cycle at the exhaust pipe position of the condenser part minus the last temperature data of the cycle is taken as the temperature change amount, and the ratio of the temperature change amount to the sampling time interval is taken as the temperature change rate. The temperature change amount and the temperature change rate are used as input data of the fuzzy PID controller. The PID-based temperature controller is an existing method in the field and will not be repeated in this embodiment. The PID control parameters are output in this way to achieve optimal control of the refrigerator inverter.

[0097] It should be noted that since the temperature data and pressure data are collected in real time, in the processing process of this embodiment, the temperature data and pressure data that have been collected are used for loop division. If the remaining temperature data or pressure data is not sufficient to constitute a complete cycle, that is, the next extreme point has not been reached, the above processing will not be performed.

[0098] At this point, this embodiment is completed.

[0099] Another embodiment of the present invention provides a PID-based refrigerator inverter optimization control system, which includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the above method steps S001 to S004 are implemented.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A PID-based refrigerator inverter optimization control method, characterized in that: The method comprises the following steps: Collect temperature data and pressure data of different parts of the refrigeration system, and obtain ambient temperature data; According to the time series change of the temperature data at the same position, several cycles of each position are obtained; according to the temperature change in each cycle at the same position, the initial heat accumulation factor of each cycle of the exhaust pipe position at each part is obtained; according to the correlation between the temperature data changes at different positions of the same part, the temperature hysteresis factor of each part is obtained, and the cycle heat accumulation factor of the exhaust pipe position at each part is obtained by adjustment; According to the correlation between the temperature data changes between the connection positions of different parts and the changes in the ambient temperature data, the temperature transfer factor between different parts is obtained, and the heat accumulation deviation of the exhaust pipe position of each part is obtained by combining the initial heat accumulation factor and the cycle heat accumulation factor; based on the changes in the pressure data of the same part in different cycles, the standard pressure sequence of each part is obtained, and the pressure changes of each part in each cycle are predicted based on the standard pressure sequence, and the final heat accumulation degree of each part in each cycle is obtained by combining the heat accumulation deviation of the exhaust pipe position of each part; According to the final heat accumulation degree of each part in each cycle, the PID control parameters are adjusted to achieve optimal control of the refrigerator inverter.

2. The PID-based refrigerator inverter optimization control method according to claim 1, characterized in that: The specific method of obtaining several cycles of each position includes: All temperature data collected at any position are used to form a temperature data sequence of the position in chronological order, and several maximum values ​​in the temperature data sequence are obtained by using the AMPD algorithm; a coordinate system is constructed with time as the horizontal axis and temperature as the vertical axis to obtain a temperature data curve corresponding to the temperature data sequence, a symmetric temperature curve is obtained by symmetrically treating the temperature data curve about the horizontal axis, and several maximum values ​​are obtained by using the AMPD algorithm for the symmetric temperature curve, and the corresponding time of the maximum value of the symmetric temperature curve is the corresponding time of several minimum values ​​in the temperature data sequence, thereby obtaining several minimum values ​​of the temperature data sequence; Calculate the mean of all temperature data in the temperature data sequence as the amplitude mean of the temperature data sequence; respectively obtain the maximum mean and minimum mean of the temperature data sequence, and calculate the absolute value of the difference with the amplitude mean, and use the extreme point type with the largest difference from the amplitude mean as the basis for period division; For the maximum value as the basis for period division, the first temperature data and all the maximum values ​​in the temperature data sequence are used as segmentation points, and the temperature data sequence is divided into several data segments through the segmentation points, and each data segment is used as a cycle.

3. The PID-based refrigerator inverter optimization control method according to claim 2, characterized in that: The initial heat accumulation factor of each cycle of the exhaust pipe position of each part is obtained by: For one cycle of the temperature data sequence at any exhaust pipe position, Initial heat accumulation factor of the second cycle The calculation method is: in, Indicates The first temperature data in the cycle, Indicates The last temperature data in the cycle, and Respectively represent Second cycle and The temperature data corresponding to the extreme point that is not the first temperature data in the cycle.

4. The PID-based refrigerator inverter optimization control method according to claim 1, characterized in that: The specific method of obtaining the temperature hysteresis factor of each part includes: Get the position of the air inlet of the condenser The time period corresponding to the first cycle is used to obtain the temperature data segment corresponding to the time period of the exhaust pipe position of the condenser, and this is used as the first temperature data segment of the air inlet position of the condenser. The control temperature sequence of the first cycle; The Pearson correlation coefficient is obtained between the first cycle and its control temperature sequence. The length of the first cycle remains unchanged and the temperature data is gradually moved backward in steps to obtain the first The moving temperature sequence of each movement in the first cycle is calculated, and the Pearson correlation coefficient between the moving temperature sequence of each movement and the control temperature sequence is calculated. The maximum value of the correlation coefficient corresponds to the step length of the first movement as the first step length of the air inlet position of the condenser. The hysteresis duration of the sub-cycle; The hysteresis duration of each cycle at the air inlet position of the condenser is obtained, and the ratio of the mean of all hysteresis durations to the quantitative mean of the temperature data of each cycle at the air inlet position of the condenser is taken as the temperature hysteresis factor of the condenser.

5. The PID-based refrigerator inverter optimization control method according to claim 1, characterized in that: The specific method for obtaining the cyclic heat accumulation factor of the exhaust pipe position at each part is as follows: in, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the temperature hysteresis factor of the condenser part, Indicates the exhaust pipe position of the condenser Initial heat accumulation factor of the sub-cycle; Obtain the cycle heat accumulation factor of each cycle at the exhaust pipe position of the evaporator.

6. The PID-based refrigerator inverter optimization control method according to claim 4, characterized in that: The temperature transfer factor between different parts is specifically obtained by: Get the exhaust pipe position of the compressor The time period corresponding to the first cycle is used to obtain the temperature data segment of the corresponding time period of the air inlet position of the condenser, and the temperature data segment of the exhaust pipe position of the compressor is obtained. The hysteresis duration of the sub-cycle; According to the position of the exhaust pipe of the compressor The hysteresis time of the first cycle is to place the exhaust pipe at the compressor position The time obtained by adding the hysteresis time to the time corresponding to any temperature data in the second cycle, and the temperature data corresponding to the air inlet position of the condenser is used as the transfer temperature data of the temperature data, and the difference between the temperature data and the transfer temperature data is calculated as the temperature transfer amount of the temperature data; the temperature data corresponding to the exhaust pipe position of the compressor is used as the temperature data corresponding to the air inlet position of the condenser. The average value of the temperature transfer of all temperature data in the cycle is taken as the value of the temperature transfer of the exhaust pipe at the compressor. Temperature transfer parameters of the secondary cycle; Combined with the ambient temperature data, the temperature transfer factor of the compressor to the condenser The calculation method is: in, Indicates the number of cycles at the exhaust pipe position of the compressor. Indicates the position of the exhaust pipe at the compressor. The temperature transfer parameter of the cycle, Indicates the position of the exhaust pipe at the compressor. The first temperature data of the cycle, Indicates the position of the exhaust pipe at the compressor. The mean value of all ambient temperature data in the time period corresponding to the cycle; Get the temperature transfer factor of the condenser section to the evaporator section.

7. The PID-based refrigerator inverter optimization control method according to claim 1, characterized in that: The specific method of obtaining the heat accumulation deviation of the exhaust pipe position at each part includes: in, Indicates the exhaust pipe position of the condenser The heat accumulation deviation of the cycle, Indicates the exhaust pipe position of the condenser The heat accumulation factor of the cycle, Indicates the position of the exhaust pipe at the compressor. The initial heat accumulation factor of the cycle, Indicates the temperature transfer factor of the compressor part to the condenser part; Obtain the heat accumulation deviation of each cycle at the exhaust pipe position of the evaporator.

8. The PID-based refrigerator inverter optimization control method according to claim 2, characterized in that: The specific method for obtaining the standard pressure sequence of each part is as follows: The pressure data of the condenser part are arranged in chronological order to form a pressure data sequence of the condenser part. Based on the cyclic division of the temperature data sequence of the exhaust pipe position of the condenser part, the pressure data sequence is cyclically divided according to the corresponding time to obtain the pressure data segments of each cycle of the condenser part. The DTW distances between the pressure data segments of all cycles are calculated pairwise, and the pressure data segment with the smallest mean DTW distance between other pressure data segments is used as the standard pressure sequence of the condenser part.

9. The PID-based refrigerator inverter optimization control method according to claim 1, characterized in that: The specific method for obtaining the final heat accumulation degree of each part in each cycle is as follows: The standard pressure series is fitted by the least square method to obtain the fitting function. For the pressure data segment of the next cycle, all the pressure data except the last one are input into the fitting function to output the pressure prediction value corresponding to the last pressure data; The final heat accumulation of the cycle The calculation method is: in, Indicates the exhaust pipe position of the condenser The heat accumulation deviation of each cycle, Indicates the condenser part The last pressure data of the cycle, Indicates the condenser part The pressure prediction value corresponding to the last pressure data of the cycle, is the effect of pressure change on temperature change.

10. A PID-based refrigerator inverter optimization control system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the PID-based refrigerator inverter optimization control method as described in any one of claims 1 to 9 are implemented.

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