A method for overheat protection of a variable frequency drive system

Abstract

The application discloses a kind of overheat protection methods for variable frequency drive system, it is related to the field of power electronics technology, the method includes: obtaining overheat protection module;Collect modeling data, build variable frequency twin model, carry out overheat protection test, generate the transient start logic of multistage protection logic;Temperature monitoring is carried out, and the starting optimization of target protection module is carried out in combination with temperature monitoring timing, generates first stage protection parameter;Overheat protection evaluation is carried out, and first stage protection fitness is generated;Protection module switching is carried out, protection optimization is carried out, and second stage protection parameter is generated;Overheat protection evaluation is carried out, and second stage protection fitness is generated, and protection module switching is repeatedly carried out until fixed protection logic is reached.The technical problem that the existing variable frequency drive system overheat protection exists is not accurate protection, and the technical effects of accurate judgment and protection to system overheat risk are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics technology, and particularly relates to a method for overheat protection of a variable frequency drive system. BACKGROUND

[0002] With the continuous improvement of industrial automation level, the variable frequency drive system has been widely used in industrial production due to its efficient and flexible speed regulation characteristics. In the working process of the variable frequency drive system, a large amount of heat is often generated due to the loss of internal power devices and the influence of external environment. When the system temperature exceeds the safety threshold, not only the normal operation of the system will be affected, but also irreversible damage to the equipment will be caused, and even safety accidents will be caused. Therefore, it is very important to effectively protect the variable frequency drive system from overheating. At present, a method for overheat protection of a variable frequency drive system mainly relies on simple temperature threshold judgment, that is, when the system temperature exceeds a certain set value, the overheat protection mechanism is triggered. This method is simple and direct, but since it is only based on a single temperature threshold for judgment, it cannot accurately reflect the overheat risk of the system under different working conditions, which may lead to premature or late protection.

[0003] At present, in the related art, the variable frequency drive system overheat protection has the technical problem of inaccurate protection. SUMMARY

[0004] The present application provides a method for overheat protection of a variable frequency drive system, which adopts a variable frequency twin model for overheat protection test, generates a multi-level protection logic instantaneous start logic, combines temperature monitoring timing to start optimization of the target protection module, evaluates the protection effect through an overheat protection fitness function, and calls an overheat continuous switching logic for protection module switching based on the evaluation result. The technical means solves the technical problem of inaccurate protection of the existing variable frequency drive system overheat protection, and achieves the technical effect of accurate judgment and protection of the system overheat risk.

[0005] The present application provides a method for overheat protection of a variable frequency drive system, which includes:

[0006] An overheat protection module of a variable frequency drive system is acquired, wherein the overheat protection module includes multi-stage protection logic; modeling data of the variable frequency drive system is collected, a variable frequency twin model is constructed, overheat protection testing is performed on the variable frequency drive system, and transient start logic of the multi-stage protection logic is generated; temperature monitoring is performed on the variable frequency drive system, and start optimization of a target protection module is performed in combination with a temperature monitoring time sequence and the transient start logic, to generate first-stage protection parameters; the first-stage protection parameters are executed, and an overheat protection fitness function is called to perform overheat protection evaluation, to generate a first-stage protection fitness; based on the first-stage protection fitness, an overheat continuous switching logic is called to perform protection module switching and protection optimization, to generate second-stage protection parameters; the second-stage protection parameters are executed and overheat protection evaluation and protection module switching are performed, until fixed protection logic is reached.

[0007] In a possible implementation, the modeling data of the variable frequency drive system is collected, the variable frequency twin model is constructed, the overheat protection testing is performed on the variable frequency drive system, and the transient start logic of the multi-stage protection logic is generated, and the following processing is performed:

[0008] An operating circuit of the variable frequency drive system is acquired, wherein the operating circuit includes a plurality of circuit elements; temperature abnormality influence testing is performed on the plurality of circuit elements by the variable frequency twin model, to generate a plurality of temperature-abnormality degree mapping data sets; multi-stage protection logic start decision is performed based on the plurality of temperature-abnormality degree mapping data sets, to generate the transient start logic, wherein the transient start logic includes start temperature thresholds of the multi-stage protection logic.

[0009] In a possible implementation, the temperature abnormality influence testing is performed on the plurality of circuit elements by the variable frequency twin model, to generate the plurality of temperature-abnormality degree mapping data sets, and the following processing is performed:

[0010] A normal temperature test sample is constructed, input into the variable frequency twin model, and a plurality of standard performance indicators of the plurality of circuit elements are recorded; a temperature abnormality test sample is constructed, input into the variable frequency twin model, and a plurality of abnormal performance indicator sets of the plurality of circuit elements are recorded; abnormality degree identification is performed based on the plurality of standard performance indicators and the plurality of abnormal performance indicator sets, to generate a plurality of abnormality degree sets; abnormality degree weighting of different circuit elements under the same temperature is performed on the plurality of abnormality degree sets, and mapping association is performed by using the temperature abnormality test sample, to generate the plurality of temperature-abnormality degree mapping data sets.

[0011] In a possible implementation, the following processing is performed:

[0012] The temperature anomaly test sample includes multiple groups of abnormal temperature samples, wherein the multiple groups of abnormal temperature samples are subjected to continuous uniform variation processing starting from the normal temperature test sample and constrained by a preset upper temperature limit.

[0013] In a possible implementation, the variable frequency drive system is subjected to temperature monitoring, and the starting optimization of the target protection module is performed in combination with the temperature monitoring timing and the instantaneous starting logic, and the following processing is performed:

[0014] The target protection module is located based on the instantaneous starting logic and the temperature monitoring timing; it is determined whether the target protection module is a protection module corresponding to the fixed protection logic, and if so, the fixed protection logic is started, and a final warning signal is generated.

[0015] In a possible implementation, the first-stage protection parameter is executed, and an overheating protection fitness function is called to perform overheating protection evaluation, to generate a first-stage protection fitness, and the following processing is performed:

[0016] After the first-stage protection parameter is executed, a temperature change timing is detected in a preset monitoring window; a temperature change rate is identified based on the temperature change timing, and a temperature change is predicted in combination with the temperature monitoring timing, to generate a first temperature prediction timing, wherein the first temperature prediction timing includes the temperature change timing; the overheating protection fitness function is called, and overheating protection evaluation is performed based on the first temperature prediction timing, to generate a first-stage protection fitness.

[0017] In a possible implementation, the following processing is performed:

[0018] The expression of the overheating protection fitness function is:

[0019] ;

[0020] The overheating protection fitness function is: is a normalized temperature stable decline index; is a normalized average temperature decline rate; is a normalized performance index stability index of a circuit element; 、 、 is a weight, and if the temperature stable decline index is less than a predetermined decline index, ; after the temperature stable decline index, the average temperature decline rate, and the performance index stability index are identified based on the first temperature prediction timing, normalization processing is performed, and the first-stage protection fitness is calculated and obtained in combination with the overheating protection fitness function.

[0021] In a possible implementation, based on the first-stage protection fitness, a persistent overheat switching logic is called to perform protection module switching and protection optimization, second-stage protection parameters are generated, and the following processing is performed:

[0022] It is determined whether the first-stage protection fitness is greater than or equal to a preset fitness; if not, a reduced temperature calculation is performed based on the first temperature prediction timing, and the persistent overheat switching logic is called to perform protection module switching, and the switching module is generated, wherein the persistent overheat switching logic includes a plurality of switching paths, and each switching path includes a reduced temperature interval and an upgraded protection module; wherein the construction steps of the persistent overheat switching logic include: performing protection performance difference analysis on the multi-stage protection modules corresponding to the multi-stage protection logic to generate a step-by-step protection performance difference index, wherein the step-by-step protection performance difference index includes a protection temperature upper limit and a protection response rate; a plurality of sets of reduced temperature intervals and upgraded protection modules are generated based on the step-by-step protection performance difference index, and the persistent overheat switching logic is established.

[0023] The application provides an overheat protection method for a variable frequency driving system. The method comprises the following steps: acquiring an overheat protection module of the variable frequency driving system, wherein the overheat protection module comprises multi-stage protection logic; collecting modeling data of the variable frequency driving system, constructing a variable frequency twin model, and performing overheat protection test on the variable frequency driving system to generate an instantaneous start logic of the multi-stage protection logic; monitoring the temperature of the variable frequency driving system, and performing start optimization of a target protection module in combination with a temperature monitoring timing and the instantaneous start logic to generate first-stage protection parameters; performing the first-stage protection parameters, calling an overheat protection fitness function to perform overheat protection evaluation, and generating a first-stage protection fitness; calling a persistent overheat switching logic based on the first-stage protection fitness to perform protection module switching and protection optimization, generating second-stage protection parameters; performing the second-stage protection parameters, performing overheat protection evaluation and protection module switching, and stopping until a fixed protection logic is reached. The method can accurately determine and protect the overheat risk of the system. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings of the embodiments of the application will be briefly introduced below. In the present application, a flowchart is used to illustrate the operations performed by the method according to the embodiments of the application. It should be understood that the foregoing or the following operations are not necessarily performed in sequence. On the contrary, various steps can be processed in reverse order or simultaneously as needed. Meanwhile, other operations can be added to these processes, or a step or several steps can be removed from these processes.

[0025] Figure 1 A flowchart of an overheat protection method for a variable frequency driving system provided by the embodiments of the application is shown in FIG. 1.

[0026] Figure 2 A flowchart for generating a plurality of temperature- abnormality degree mapping data sets in a method for overheat protection of a variable frequency drive system is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The above description is only a summary of the technical solutions of the present application. In order to make the technical solutions of the present application more clear, the embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below.

[0028] In order to make the purposes, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings, and the described embodiments should not be regarded as limiting the present application. All other embodiments obtained by those skilled in the art without making creative labor fall within the scope of protection of the present application.

[0029] In the following description, "some embodiments" are related to a subset of all possible embodiments, but it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict, and the term "first\second" involved only distinguishes similar objects, and does not represent a specific order of the objects. The terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or modules not clearly listed or inherent to these processes, methods, products or devices. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application.

[0030] An overheat protection method for a variable frequency drive system is provided in an embodiment of the present application, as shown in the method comprises: Figure 1

[0031] ​Step S100, obtain the overheat protection module of the variable frequency drive system, wherein the overheat protection module comprises multi-level protection logic. Specifically, the variable frequency drive system is a power electronic system capable of adjusting the speed of the motor, which is composed of frequency converters, motors, controllers and the like. Since the motor generates heat during operation, effective overheat protection is needed to ensure the safe operation of the variable frequency drive system. The overheat protection module is a functional module in the variable frequency drive system, which is used to monitor and prevent system overheating, including temperature sensors, controllers and actuators and other components, for real-time monitoring of system temperature and taking appropriate protective measures as needed. Analyze the structure and function of the variable frequency drive system, determine the location and composition of the overheat protection module, identify and obtain the overheat protection module in the variable frequency drive system, which has multi-level protection logic. The multi-level protection logic is a hierarchical protection strategy that gradually and orderly executes protection measures by setting different protection levels and trigger conditions to minimize damage to the system caused by overheating and extend the service life of the system. Analyze the specific content and trigger conditions of the multi-level protection logic, for example, the first level can be to reduce output power to reduce heat generation, the second level can be to start the heat dissipation system to accelerate heat dissipation, and the third level can be to temporarily stop running to avoid further damage.

[0032] Step S200, collect the modeling data of the variable frequency drive system, build a variable frequency twin model, test the overheat protection of the variable frequency drive system, and generate the instantaneous start logic of the multi-level protection logic. Specifically, identify the key parameters and variables in the variable frequency drive system, such as temperature, current, voltage, frequency, etc., use sensors and data acquisition devices to obtain the values of these parameters and variables in real time, and record them as modeling data. According to the collected modeling data, use mathematical modeling methods and simulation software to build a twin model of the variable frequency drive system, which is used to simulate the dynamic behavior and performance of the actual system, including temperature distribution, heat generation and dissipation, etc. Simulate different overheat conditions on the variable frequency twin model, such as temperature changes, load changes, etc., analyze the response and performance of the variable frequency twin model, and record the key data and results during the test process, such as temperature curves, etc. According to the results and analysis of the overheat protection test, determine the trigger conditions and thresholds of each level of protection logic, design corresponding algorithms and control strategies, and generate the instantaneous start logic of the multi-level protection logic. The instantaneous start logic refers to the algorithm and control strategy used to quickly and accurately trigger and execute the corresponding protection measures in the case of overheating.

[0033] In a possible implementation, the modeling data of the variable frequency drive system is collected, a variable frequency twin model is constructed, an overheat protection test is performed on the variable frequency drive system, and transient start logic of the multi-level protection logic is generated. Step S200 further includes step S210 of obtaining an operating circuit of the variable frequency drive system, wherein the operating circuit includes a plurality of circuit elements. Specifically, the circuit diagram and related technical documents of the variable frequency drive system are collected, key circuit elements in the operating circuit such as capacitors, inductors, resistors, semiconductor switches, etc. are identified and listed, and the specifications, performance parameters and working environment requirements of each circuit element are sorted. Step S220, the temperature abnormality influence test is performed on the plurality of circuit elements by the variable frequency twin model, and a plurality of temperature- abnormality mapping data sets are generated. Specifically, the working state of the circuit element under different temperature conditions is simulated by using the constructed variable frequency twin model, the performance change and abnormal behavior of the circuit element under different temperatures are monitored and recorded, and the temperature- abnormality mapping data set of each circuit element is generated according to the test result, the temperature- abnormality mapping data set describes the relationship between temperature and abnormality degree of the circuit element. Step S230, multi-level protection logic start decision is made based on the plurality of temperature- abnormality mapping data sets, and the transient start logic is generated, wherein the transient start logic includes the start temperature threshold of the multi-level protection logic. Specifically, the temperature- abnormality mapping data set is analyzed, the abnormal behavior and risk points of the circuit element under different temperatures are identified, and the start temperature threshold of the multi-level protection logic is set based on the tolerance temperature of the circuit element, the system safety requirement and the operation efficiency, etc. according to the analysis result, the transient start logic is generated, and the transient start logic describes the protection measures and action sequence that should be started under different temperature thresholds. This implementation accurately simulates and analyzes the behavior and performance of the variable frequency drive system under various temperature conditions by constructing the variable frequency twin model and performing the temperature abnormality influence test, which helps to deeply understand the sensitivity and vulnerability of the system to temperature abnormality, and achieves the technical effect of generating more accurate and effective transient start logic of multi-level protection logic.

[0034] As Figure 2In a possible implementation, as shown, the temperature anomaly influence test on the plurality of circuit elements by the frequency conversion twin model generates a plurality of temperature- abnormality mapping data sets, and step S220 further includes steps S221-S224. Step S221: constructing normal temperature test samples, inputting the frequency conversion twin model, and recording a plurality of standard performance indicators of the plurality of circuit elements. Specifically, a set of normal temperature test samples is constructed according to the normal operating conditions of the frequency conversion drive system and the specifications of the circuit elements, that is, test data simulating the operation of the frequency conversion drive system under normal temperature conditions. The normal temperature test samples are input into the frequency conversion twin model to simulate the operating state of the circuit elements under normal operating temperature. During the simulation, a plurality of standard performance indicators of each circuit element are recorded, that is, key indicators reflecting the performance of the circuit elements under normal operating conditions, such as current, voltage, power loss, and the like. Step S222: constructing temperature anomaly test samples, inputting the frequency conversion twin model, and recording a plurality of abnormal performance indicator sets of the plurality of circuit elements. Specifically, a set of temperature anomaly test samples is constructed, that is, test data simulating the operation of the frequency conversion drive system under abnormal temperature conditions, for simulating the operating state of the circuit elements under different abnormal temperatures. The temperature anomaly test samples are input into the frequency conversion twin model to simulate the performance changes of the circuit elements under abnormal temperatures. During the simulation, a plurality of performance indicators of each circuit element under abnormal temperatures are recorded to form an abnormal performance indicator set, that is, a set of indicators reflecting the performance changes of the circuit elements under abnormal temperatures. Step S223: identifying abnormality degrees based on the plurality of standard performance indicators and the plurality of abnormal performance indicator sets, and generating a plurality of abnormality degree sets. Specifically, the performance indicators of each circuit element under normal temperature and abnormal temperature are compared to identify abnormality degrees, which can be quantified by calculating the change rate of the performance indicators, the degree of deviation from the standard value, and the like. For each circuit element, an abnormality degree set containing the abnormality degree values under different abnormal temperatures is generated. Step S224: weighting abnormality degrees of different circuit elements under the same temperature for the plurality of abnormality degree sets, and mapping and correlating the temperature anomaly test samples to generate the plurality of temperature- abnormality mapping data sets. Specifically, under the same temperature, the importance and sensitivity of different circuit elements in the system are analyzed, the abnormality degrees are weighted, the weighted abnormality degrees are mapped and correlated with the corresponding temperature anomaly test samples to generate temperature- abnormality mapping data sets, and for each temperature point, there is an abnormality degree set corresponding thereto, forming a complete temperature- abnormality mapping relationship. This implementation quantitatively expresses the performance deviation degree of the circuit elements under abnormal temperatures by identifying abnormality degrees, and comprehensively reflects the overall abnormality degree of the frequency conversion drive system by weighting a plurality of abnormality degree sets, thereby achieving the technical effect of improving the accuracy of temperature anomaly analysis of the frequency conversion drive system.

[0035] In a possible implementation, step S222 further includes step S2221, the temperature abnormality test sample includes a plurality of sets of abnormal temperature samples, wherein the plurality of sets of abnormal temperature samples are obtained by performing continuous uniform variation processing starting from the normal temperature test sample and subject to a preset upper temperature limit. Specifically, the temperature abnormality test sample is a data set for simulating the operation of the system under different abnormal temperature conditions. The plurality of sets of abnormal temperature samples start from the normal temperature test sample, that is, the initial temperature abnormality test sample is determined based on the normal temperature test sample, combined with the operation experience of the actual system or expert suggestions, etc. The preset upper temperature limit is the maximum temperature value that the system can withstand according to the physical characteristics of the system, the material tolerance, and the safety specifications, etc. Exceeding this value will cause system damage or failure. The continuous uniform variation processing refers to generating a variation step according to the test requirements and accuracy, starting from the initial temperature abnormality test sample, gradually increasing the temperature according to the variation step, generating a series of new temperature points, and each new temperature point serves as a new abnormal temperature sample. When generating a new temperature point, it is ensured that the preset upper temperature limit will not be exceeded. This implementation generates a plurality of sets of abnormal temperature samples through continuous uniform variation processing, covering various conditions from slight abnormality to severe abnormality, and achieves the technical effect of ensuring the comprehensiveness and accuracy of the test.

[0036] In step S300, the temperature of the variable frequency drive system is monitored, and the starting optimization of the target protection module is performed in combination with the temperature monitoring time sequence and the instantaneous starting logic to generate the first-stage protection parameter. Specifically, the temperature monitoring module in the variable frequency drive system is enabled, which is used to monitor the temperature of the variable frequency drive system in real time and is composed of a temperature sensor, a data collector and a data processing unit. The temperature monitoring module transmits the monitored temperature data to the control system or data analysis platform in real time through the set sampling frequency. The control system or data analysis platform performs time sequence analysis on the collected temperature monitoring data to understand the trend, rate and periodicity of temperature change. According to the current temperature monitoring time sequence data, the current thermal state of the system and the possible development trend are judged, and the target protection module (the specific protection module or device that needs to be started in the case of overheating) and the corresponding protection measures are determined by optimization calculation through algorithms or expert systems in combination with the instantaneous starting logic. According to the optimization result, the first-stage protection parameter is generated, which is a parameter or instruction for guiding the actual system to execute the protection measures, including the protection module to be started, the specific execution mode of the protection measures (such as the percentage of reducing the output power, the operation mode of the heat dissipation system, etc.) and the time node of execution, etc.

[0037] In a possible implementation, the variable frequency drive system is temperature monitored, and the starting optimization of the target protection module is performed in combination with the temperature monitoring timing and the instantaneous starting logic. Step S300 further includes step S310 of locating the target protection module based on the instantaneous starting logic and the temperature monitoring timing. Specifically, the temperature monitoring module collects temperature data of key parts of the variable frequency drive system according to a preset timing, matches the collected temperature data with a time sequence, analyzes the trend and speed of temperature change, and selects a protection module that is most matched with the current temperature condition from a preset protection module library according to the instantaneous starting logic. Step S320 judges whether the target protection module is a protection module corresponding to fixed protection logic. If yes, the fixed protection logic is started, and a final warning signal is generated. Specifically, it is checked whether the target protection module belongs to the category of fixed protection logic. The fixed protection logic refers to an extreme protection measure (stopping system operation or starting a backup device) taken when the system temperature cannot be effectively controlled after all available protection modules and parameters are tried in the process of overheating protection, and is used to avoid serious damage or failure of the system caused by overheating. If the target protection module belongs to the category of fixed protection logic, the logic is immediately started, including stopping system operation, starting a backup device, or taking other emergency measures. At the same time of starting the fixed protection logic, a final warning signal, i.e., a highest-level warning signal, is generated to remind that the system has entered an emergency state and needs to be further processed or responded. This implementation generates a final warning signal by taking the fixed protection logic as the last line of defense, and achieves the technical effects of improving the reliability and maintainability of the system.

[0038] Step S400, execute the first stage protection parameter, and call the overheat protection fitness function to evaluate the overheat protection, and generate the first stage protection fitness. Specifically, the control system starts the corresponding target protection module according to the first stage protection parameter, for the instruction of reducing the output power, adjusts the output of the frequency converter, reduces the thermal load of the motor; for the instruction of the heat dissipation system, starts or adjusts the rotating speed of the heat dissipation fan, and enhances the heat dissipation effect. Monitor the execution process to ensure that the protection module works normally according to the predetermined parameters. After the first stage protection parameter is executed, the pre-defined overheat protection fitness function is called, and the effect of the overheat protection is evaluated according to the real-time state of the system (such as temperature, current, voltage, etc.) and the executed protection measures, wherein the overheat protection fitness function is a function for evaluating the effect of the overheat protection, and a fitness value is calculated according to the real-time state of the system and the executed protection measures to quantify the good and bad of the protection effect. The overheat protection fitness function can include multiple evaluation indexes, such as the rate of temperature reduction, the stability of system operation, etc. According to the calculation result of the overheat protection fitness function, the first stage protection fitness is generated, which is used to evaluate the actual effect of the first stage protection measures in reducing the overheat risk of the system, maintaining the stable operation of the system, etc.

[0039] In a possible implementation, the first-stage protection parameter is executed, and an overheat protection fitness function is called to perform overheat protection evaluation, generating a first-stage protection fitness, and step S400 further includes step S410, after the first-stage protection parameter is executed, detecting a temperature change time sequence in a preset monitoring window. Specifically, a time period is set as the preset monitoring window, for observing the change of the system temperature in the time period, and in the preset monitoring window, the temperature change time sequence of the system is continuously monitored and recorded by a temperature sensor or the like. Step S420, temperature change rate identification is performed based on the temperature change time sequence, and temperature change prediction is performed in combination with the temperature monitoring time sequence, generating a first temperature prediction time sequence, wherein the first temperature prediction time sequence includes the temperature change time sequence. Specifically, by analyzing the temperature change time sequence, the rate of temperature change (i.e., temperature change rate) is calculated, which represents the amount of temperature change per unit time and reflects the speed of temperature change. The temperature change rate is combined with the temperature monitoring time sequence to predict future temperature changes by comprehensively considering the heat dissipation capacity of the system, the environmental temperature and the like, and based on the analysis result, a prediction time sequence including the temperature change time sequence, i.e., the first temperature prediction time sequence, is generated. Step S430, the overheat protection fitness function is called, and overheat protection evaluation is performed based on the first temperature prediction time sequence, generating a first-stage protection fitness. Specifically, the first temperature prediction time sequence is taken as input, and the overheat protection fitness function is calculated to obtain the fitness of the first-stage protection strategy, and the result output by the overheat protection fitness function is the first-stage protection fitness, reflecting the effect and efficiency of the first-stage protection strategy in reducing the system temperature. This implementation introduces the temperature change rate when performing overheat protection evaluation, and the temperature change rate is combined to predict the temperature change, thereby improving the accuracy of the temperature prediction time sequence, and further achieving the technical effect of improving the accuracy of overheat protection evaluation.

[0040] In a possible implementation, step S430 further includes step S431, and the expression of the overheat protection fitness function is:

[0041] ;

[0042] is the overheat protection fitness function; is the normalized temperature stable decline index; is the normalized average temperature decline rate; is the normalized performance index stability index of the circuit element; 、 、 is the weight, if the temperature stable decline index is less than a predetermined decline index, Specifically, the temperature stable drop index is used to measure the stability and efficiency of temperature drop, which can be calculated by the proportion of temperature drop nodes in the first temperature prediction time sequence, the average temperature drop rate represents the average speed of temperature drop, and the performance index stability index is a comprehensive index reflecting the performance stability of the circuit element in the overheat protection process. If the temperature stable drop index is less than the predetermined drop index, the weight is adjusted to ensure the effectiveness of the overheat protection mechanism. In step S432, the temperature stable drop index, the average temperature drop rate and the performance index stability index are identified based on the first temperature prediction time sequence, and then normalized processing is performed, and the first stage protection fitness is calculated based on the overheat protection fitness function. Specifically, based on the first temperature prediction time sequence data, the temperature stable drop index, the average temperature drop rate and the performance index stability index are identified, and these indexes are normalized to facilitate unified calculation in the overheat protection fitness function. The first stage protection fitness is calculated based on the overheat protection fitness function and the normalized index value, which is a comprehensive evaluation result reflecting the effect of the overheat protection mechanism in the first stage. This implementation mode comprehensively considers multiple related indexes and gives different weights, which achieves the technical effect of comprehensive and objective overheat protection evaluation.

[0043] In step S500, based on the first stage protection fitness, the overheat continuous switching logic is called to perform protection module switching and protection optimization, and the second stage protection parameter is generated. Specifically, if the first stage protection fitness does not reach the preset standard or the system temperature is still rising, the overheat continuous switching logic is called, which is a preset algorithm or strategy. According to the current system thermal state, the executed protection measures and the first stage protection fitness, it is determined whether it is necessary to switch to a higher level protection module and how to switch the module. According to the judgment result of the overheat continuous switching logic, if the module switching is needed, the corresponding switching operation is performed, including closing the currently running protection module, starting a new protection module, or adjusting the cooperative working mode of multiple protection modules. After the new protection module is started, the optimization calculation is performed according to the new system state and protection strategy. The goal of the optimization calculation is to find the optimal protection parameter combination under the current system state to maximize the reduction of system overheat risk and maintain the stable operation of the system. According to the result of the optimization calculation, the second stage protection parameter is generated.

[0044] In a possible implementation, based on the first-stage protection fitness, a persistent overheat switching logic is called to perform protection module switching and protection optimization, and second-stage protection parameters are generated. Step S500 further includes step S510 of judging whether the first-stage protection fitness is greater than or equal to a preset fitness. Specifically, the preset fitness is a threshold value set in advance, which is used to judge whether the first-stage protection fitness meets the requirements. Step S520, if not, a temperature reduction calculation is performed based on the first temperature prediction time sequence, and the persistent overheat switching logic is called to perform protection module switching, and the switching module is generated, where the persistent overheat switching logic includes a plurality of switching paths, and each switching path includes a temperature reduction interval and an upgraded protection module. Specifically, if the first-stage protection fitness is less than the preset fitness, it indicates that the current protection module or strategy is not effective. According to the temperature reduction calculation based on the first temperature prediction time sequence, the target temperature range or the temperature reduction speed to be reached is determined, the persistent overheat switching logic is called, a suitable switching path is selected, and the protection module is switched to generate a new switching module. The persistent overheat switching logic includes a plurality of possible switching paths, which are used to select a suitable protection module according to actual needs during overheat protection.

[0045] In step S510, the persistent overheat switching logic includes steps S511 of performing protection performance difference analysis on the multi-stage protection logic corresponding to the multi-stage protection module to generate a step-by-step protection performance difference index, where the step-by-step protection performance difference index includes a protection temperature upper limit and a protection response rate. Specifically, the performance of the multi-stage protection module is evaluated, and the differences of the protection temperature upper limit and the protection response rate of each stage of protection module are analyzed. The multi-stage protection module refers to a plurality of levels of protection modules, and the protection ability and response speed of each level are different. The protection temperature upper limit refers to the maximum temperature that each protection module can withstand, and the protection response rate refers to the time required from overheat detection to taking protection measures. Step S512, based on the step-by-step protection performance difference index, a plurality of temperature reduction intervals and upgraded protection modules are generated to establish the persistent overheat switching logic. Specifically, according to the performance difference of each stage of protection module, different temperature reduction intervals are set, and the temperature reduction interval (when the temperature reaches or exceeds a certain threshold value, the protection module needs to be switched to the next higher level) is matched with the corresponding upgraded protection module (in the overheat protection process, when the current protection module cannot meet the requirements, the protection module needs to be switched to the higher level), and the persistent overheat switching logic is constructed. This implementation ensures that the system can quickly and accurately respond during overheat protection, and achieves the technical effect of reducing the damage caused by overheat to the equipment.

[0046] In step S600, the second-stage protection parameter is executed, and overheat protection evaluation and protection module switching are performed until fixed protection logic is reached. Specifically, after the control system receives the second-stage protection parameter, the corresponding protection module is adjusted according to the parameter instruction, and the execution process is monitored to ensure that the protection module works normally according to the predetermined parameter. After the second-stage protection parameter is executed, the overheat protection fitness function is used to evaluate the protection effect of this stage, and the second-stage protection fitness is generated according to the calculation result of the overheat protection fitness function. The second-stage protection fitness quantitatively represents the effect of the second-stage protection parameter in reducing the system overheat risk and maintaining the stable operation of the system. It is evaluated whether the second-stage protection fitness meets the preset standard. If it does not meet the preset standard, and the system temperature is still abnormal or there is a further upward trend, the protection module switching is continued, and the next protection module to be activated is selected according to the overheat continuous switching logic. The above process is repeated until the protection module and parameter that can effectively reduce the system overheat risk and maintain the stable operation of the system are found. If the system temperature cannot be effectively controlled after multiple switching and optimization, or the protection module has been exhausted, the fixed protection logic is entered, that is, the operation of the variable frequency drive system is stopped, or the standby frequency converter is started to maintain the basic operation of the system to avoid further overheat damage. The embodiment of the present application uses the variable frequency twin model to perform overheat protection test, generates the instantaneous start logic of the multi-stage protection logic, combines the temperature monitoring time sequence to perform start optimization of the target protection module, evaluates the protection effect through the overheat protection fitness function, and calls the overheat continuous switching logic to switch the protection module based on the evaluation result. The technical problems of inaccurate protection of the existing variable frequency drive system overheat protection are solved, and the technical effects of accurately judging and protecting the system overheat risk are achieved.

[0047] The specific embodiments described above do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, 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 application should be included in the protection scope of the present application. In some cases, the actions or steps described in the present application can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

Claims

1. A method for overheat protection in a variable frequency drive system, characterized in that, The method includes: Obtain the overheat protection module of the variable frequency drive system, wherein the overheat protection module includes multi-level protection logic; The modeling data of the variable frequency drive system is collected, a variable frequency twin model is constructed, an overheat protection test is performed on the variable frequency drive system, and the instantaneous start logic of the multi-level protection logic is generated. Temperature monitoring is performed on the variable frequency drive system, and the startup optimization of the target protection module is performed by combining the temperature monitoring timing with the instantaneous startup logic to generate the first stage protection parameters; The first-stage protection parameters are executed, and the overheat protection fitness function is called to evaluate the overheat protection and generate the first-stage protection fitness. Based on the first-stage protection adaptability, the overheating continuous switching logic is invoked to switch protection modules and optimize protection, generating the second-stage protection parameters. The second-stage protection parameters are executed, and overheat protection evaluation and protection module switching are performed until the fixed protection logic is reached. Specifically, the first-stage protection parameters are executed, and the overheat protection fitness function is called to evaluate the overheat protection and generate the first-stage protection fitness, including: After executing the first stage protection parameters, the timing of temperature changes is detected and recorded in the preset monitoring window; Based on the temperature change time series, the temperature change rate is identified, and combined with the temperature monitoring time series, temperature change is predicted to generate a first temperature prediction time series, wherein the first temperature prediction time series includes the temperature change time series. The overheat protection fitness function is invoked to evaluate the overheat protection based on the first temperature prediction time series, and a first-stage protection fitness is generated. The expression for the overheat protection fitness function is as follows: ； The overheat protection fitness function is... This is the normalized indicator of stable temperature decrease. This represents the normalized average rate of temperature decrease. The stability index is the performance indicator of the circuit element after normalization. , , As a weight, if the temperature stability decrease index is less than the predetermined decrease index, ; Based on the first temperature prediction time series, the temperature stability decrease index, average temperature decrease rate and performance index stability index are identified and normalized. Combined with the overheat protection fitness function, the first stage protection fitness is calculated and obtained. Based on the first-stage protection adaptability, the overheating continuous switching logic is invoked to switch protection modules and optimize protection, generating second-stage protection parameters, including: Determine whether the protection fitness of the first stage is greater than or equal to the preset fitness. If not, the temperature reduction calculation is performed based on the first temperature prediction timing, and the overheating continuous switching logic is called to switch the protection module and generate a switching module. The overheating continuous switching logic includes multiple switching paths, and any switching path includes a temperature reduction range and an upgraded protection module. The construction steps of the overheating continuous switching logic include: A protection performance difference analysis is performed on the multi-level protection modules corresponding to the multi-level protection logic to generate a step-by-step protection performance difference index, wherein the step-by-step protection performance difference index includes the upper limit of protection temperature and the protection response rate; Based on the performance difference index of the progressive protection, multiple sets of temperature reduction ranges and upgraded protection modules are generated, and the overheating continuous switching logic is established.

2. The overheat protection method for a variable frequency drive system as described in claim 1, characterized in that, Collect modeling data of the variable frequency drive system, construct a variable frequency twin model, perform overheat protection testing on the variable frequency drive system, and generate the instantaneous start logic of the multi-level protection logic, including: Obtain the operating circuit of the variable frequency drive system, wherein the operating circuit includes multiple circuit elements; The temperature anomaly effect test of the multiple circuit components is carried out using the frequency conversion twin model, generating multiple temperature-anomaly degree mapping datasets; Based on the multiple temperature-anomaly mapping datasets, a multi-level protection logic activation decision is made to generate the instantaneous activation logic, wherein the instantaneous activation logic includes the activation temperature threshold of the multi-level protection logic.

3. The overheat protection method for a variable frequency drive system as described in claim 2, characterized in that, The temperature anomaly impact test of the multiple circuit components was conducted using the aforementioned frequency conversion twin model, generating multiple temperature-anomaly degree mapping datasets, including: Construct a normal temperature test sample, input it into the frequency conversion twin model, and record multiple standard performance indicators of the multiple circuit elements; Construct a temperature anomaly test sample, input it into the frequency conversion twin model, and record a set of multiple abnormal performance indicators of the multiple circuit elements; Anomaly identification is performed based on the multiple standard performance indicators and multiple sets of abnormal performance indicators to generate multiple sets of anomalies. The anomaly degree of the multiple anomaly degree sets is weighted according to the anomaly degree of different circuit components at the same temperature, and the temperature anomaly test samples are used to perform mapping association to generate the multiple temperature-anomaly degree mapping datasets.

4. The overheat protection method for a variable frequency drive system as described in claim 3, characterized in that, The abnormal temperature test sample includes multiple sets of abnormal temperature samples, wherein the multiple sets of abnormal temperature samples are obtained by continuous uniform variation processing, starting from the normal temperature test sample and constrained by a preset upper temperature limit.

5. The overheat protection method for a variable frequency drive system as described in claim 1, characterized in that, The method further includes: monitoring the temperature of the variable frequency drive system, optimizing the startup of the target protection module by combining the temperature monitoring timing with the instantaneous startup logic; and performing temperature monitoring of the variable frequency drive system temperature monitoring. The target protection module is located based on the instantaneous startup logic and the temperature monitoring timing. Determine whether the target protection module is the protection module corresponding to the fixed protection logic. If so, activate the fixed protection logic and generate the final warning signal.

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