A frequency converter control method, device and control system

Abstract

The present application relates to the field of inverter control technology, and specifically to an inverter control method, device and control system, the method comprising: real-time acquisition of the input and output current data of the inverter; determining the abnormal values ​​of the input and output current data in each time period; determining the abnormal degree of the output current data in each time period based on the difference between the two abnormal values ​​in each time period and the degree of mutation of the output current data in each time period; determining the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period based on the abnormal degree in each time period and its adjacent time period, and in combination with the difference in the output current data between each time period and its adjacent time period; determining the power parameter of the power approach law in the sliding membrane controller in the inverter in the next time period. The present application aims to improve the suppression effect of jitter while maintaining a good approach speed and improving the accuracy of inverter control.

Description

Technical Field

[0001] The present application relates to the technical field of inverter control, and in particular to an inverter control method, device and control system. Background Art

[0002] The inverter is a device that converts industrial frequency power into AC power of various frequencies to achieve variable speed operation of the motor. Inverters are commonly used in chemical, oil and gas, and sewage treatment industries to optimize motor control, improve energy efficiency, and increase production efficiency. Therefore, the stability and precision control of the inverter is crucial in practical applications.

[0003] ABB inverters have been widely used in industrial equipment due to their high reliability, high efficiency, energy saving and good safety. ABB inverters mainly use direct torque control (DTC) to control the magnetic flux and torque of the motor to achieve high-performance speed regulation of AC motors. ABB inverters usually use sliding film controllers to reduce the impact of jitter during the control process. The size of the power parameter in the sliding film controller will affect the control effect of the inverter. However, the power parameter in the traditional sliding film controller is usually a fixed value, resulting in poor control of jitter. Therefore, in the actual production process, it is necessary to adjust the size of the power parameter in time to improve the accuracy of the inverter control. Summary of the invention

[0004] In view of the above, it is necessary to provide a frequency converter control method, device and control system, which, compared with the traditional frequency converter control method, can improve the vibration suppression effect while maintaining a good approach speed and improve the accuracy of the frequency converter control:

[0005] In a first aspect, an embodiment of the present application provides a method for controlling a frequency converter, the method comprising the following steps:

[0006] Collect the input current data and output current data of the inverter in real time;

[0007] Taking each preset time length as a time period, based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input current and output current in the time series, and combining the significance of the high-frequency signal of the input and output current data in the frequency domain, the abnormal values ​​of the input and output current data in each time period are determined respectively;

[0008] Determine the abnormality degree of the output current data in each time period based on the difference in abnormal values ​​between the input current data and the output current data in each time period and the degree of mutation of the output current data in each time period;

[0009] Based on the abnormality degree in each time period and its adjacent time period, and in combination with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period;

[0010] Based on the influence index in the current time period, a power parameter of a power reaching law in a synovial controller in the frequency converter in the next time period is determined.

[0011] In one embodiment, the process of determining the outlier is as follows:

[0012] Arrange all peak values ​​and all valley values ​​of the input current data in each time period in time sequence to form a peak-valley sequence;

[0013] Based on the distribution of the difference between each data and its adjacent data in each peak-valley sequence, the difference between the peak value and the valley value of the input current data in each time period is determined;

[0014] Calculate the autocorrelation coefficient of each peak-valley sequence at each time delay, and record the average of the absolute values ​​of the autocorrelation coefficients of each peak-valley sequence at all time delays as the autocorrelation mean;

[0015] Obtaining the median value of the frequency in the frequency spectrum of the input current data in each time period, and taking the ratio of the sum of the amplitudes of all frequencies in each frequency spectrum that are greater than the median value to the sum of the amplitudes of all frequencies in each frequency spectrum as the high-frequency signal significance of the input current data in each time period;

[0016] The abnormal value is respectively proportional to the difference value and the significance of the high-frequency signal, and inversely proportional to the autocorrelation mean;

[0017] For the output current data in each time period, the abnormal value of the output current data in each time period is obtained by adopting the same method as that for obtaining the abnormal value of the input current data in each time period.

[0018] In one embodiment, the process of determining the difference value is:

[0019] The difference between each data in each peak-valley sequence and its previous adjacent data is calculated respectively, recorded as the forward difference; the difference between each data and its subsequent adjacent data is recorded as the backward difference, and the mean of the forward difference and the backward difference of each data is calculated, recorded as the phase difference mean;

[0020] The cumulative sum of the phase difference mean values ​​of all data in each peak-valley sequence is taken as the difference value between the peak value and the valley value of the input current data in each time period.

[0021] In one embodiment, the expression of the outlier is:

[0022] ; In the formula, represents the abnormal value of the input current data in the i-th time period; represents the difference between the peak value and the valley value of the input current data in the i-th time period; Indicates the significance of high-frequency signals of input current data in the i-th time period; Represents the autocorrelation mean of the peak-to-valley sequence in the i-th time period; α represents a value preset to be greater than 0.

[0023] In one embodiment, the process of determining the abnormality degree is:

[0024] Calculate the average value of the abnormal value of the input current data and the abnormal value of the output current data in each time period;

[0025] The difference between the abnormal values ​​of the input current data and the output current data in each time period and the fusion result of the average value are used as the difference value of the stable state between the input and output currents in each time period;

[0026] A mutation point detection algorithm is used to obtain the statistics corresponding to each mutation point in the output current data in each time period, and the accumulated value of the statistics corresponding to all mutation points in the output current data in each time period is used as the mutation value of the output current data in each time period;

[0027] The abnormality degree of the output current data in each time period is obtained by combining the difference value and the mutation value.

[0028] In one embodiment, the abnormality level is the product of the distinction value and the mutation value.

[0029] In one embodiment, the process of determining the impact index is as follows:

[0030] Arrange all output current data in each time period in time sequence to form each output current data sequence;

[0031] Calculate the distance between each time period and the output current data sequence of its adjacent time period;

[0032] The influence index is positively correlated with the distance, the abnormality level in each time period, and the abnormality level in the adjacent time period of each time period.

[0033] In one embodiment, the calculation formula of the power parameter is:

[0034] ; In the formula, Q represents the power parameter of the power reaching law in the sliding film controller in the inverter in the next time period; X represents the normalized result of the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in the current time period.

[0035] In a second aspect, an embodiment of the present application further provides a frequency converter control device, the device comprising:

[0036] Current acquisition module, used to collect the input current data and output current data of the inverter in real time;

[0037] The interference analysis module is used to take each preset time length as a time period, and determine the abnormal values ​​of the input and output current data in each time period based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input and output currents in the time series, and combined with the significance of the high-frequency signals of the input and output current data in the frequency domain;

[0038] Determine the abnormality degree of the output current data in each time period based on the difference in abnormal values ​​between the input current data and the output current data in each time period and the degree of mutation of the output current data in each time period;

[0039] Based on the abnormality degree in each time period and its adjacent time period, and in combination with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period;

[0040] The control parameter determination module is used to determine the power parameter of the power reaching law in the synovial controller in the inverter in the next time period based on the influence index in the current time period.

[0041] In a third aspect, an embodiment of the present application further provides a frequency converter control system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the frequency converter control methods described above are implemented.

[0042] This application has at least the following beneficial effects:

[0043] The present application is based on the fluctuation of all peak values ​​and all valley values ​​of input and output current data in each time period, as well as the autocorrelation of input current and output current in time series, and combined with the significance of high-frequency signals of input and output current data in the frequency domain, to determine the abnormal values ​​of input and output current data in each time period respectively; fully considers multiple manifestations of irregular fluctuation characteristics of input and output current data, and improves the accuracy of fluctuation characteristic analysis of input and output current data;

[0044] Furthermore, based on the difference in abnormal values ​​between the input current data and the output current data in each time period, and the degree of mutation of the output current data in each time period, the degree of abnormality of the output current data in each time period is determined; the difference in fluctuation characteristics between the input current and the output current, and the mutation of the output current itself are comprehensively analyzed, thereby improving the accuracy of the analysis of the degree of abnormality of the output current data;

[0045] Furthermore, based on the abnormality degree in each time period and its adjacent time period, and combined with the difference in output current data between each time period and its adjacent time period, the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period is determined; the difference in the abnormality degree of output current between different time periods is combined to improve the accuracy of analyzing the influence degree of power supply fluctuation and electromagnetic interference on the inverter;

[0046] Based on the influence index in the current time period, the power parameters of the power reaching law in the sliding film controller in the inverter in the next time period are determined; according to the severity of the jitter phenomenon caused by power supply fluctuations and electromagnetic interference, the power parameters of the power reaching law in the sliding film controller are optimized, which can improve the suppression effect of jitter while ensuring a good approach speed, thereby improving the accuracy of inverter control. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 A flowchart of a frequency converter control method provided by one embodiment of the present application;

[0049] Figure 2 This is a simplified structural diagram of the ABB inverter equipment;

[0050] Figure 3 Schematic diagram for current data peak extraction;

[0051] Figure 4 A schematic diagram of a flow chart for determining abnormal values ​​of input current data;

[0052] Figure 5 A schematic diagram of a flow chart for determining the abnormality of output current data;

[0053] Figure 6 This is a schematic diagram of the process of determining the impact index;

[0054] Figure 7 To optimize the output current curve of the inverter before;

[0055] Figure 8 This is the output current curve of the inverter after optimization. DETAILED DESCRIPTION

[0056] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a concrete manner.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It should be understood that, unless otherwise specified, " / " means or.

[0058] It should also be noted that the terms "first" and "second" in the present application are used to distinguish similar objects rather than to describe a specific order or sequence.

[0059] The following is a detailed description of a specific scheme of a frequency converter control method, device and control system provided by the present application in conjunction with the accompanying drawings.

[0060] See also Figure 1 , which shows a flow chart of a frequency converter control method provided by an embodiment of the present application, the method comprising the following steps:

[0061] Step 1: collect the input current data and output current data of the inverter in real time.

[0062] The working principle of the frequency converter is to first convert the industrial frequency AC power into DC power, and then convert the DC power into AC power with adjustable frequency and voltage to supply the motor and control the speed of the motor. The simplified structural diagram of the ABB frequency converter device in this application is shown in Figure 2 shown.

[0063] Figure 2 The three arrows represent AC power, and the two arrows represent DC power. The rectifier part is usually composed of a rectifier bridge, which converts the input AC power into DC power. The DC power is smoothed in the filter circuit to reduce voltage fluctuations. The DC power is converted into adjustable frequency AC power in the inverter part and finally transmitted to the load side. Direct torque control (DTC) is integrated inside the controller to achieve direct and fast control of the motor torque.

[0064] Since the inverter control process is susceptible to power fluctuations and electromagnetic interference, the present application uses a current sensor to collect the three-phase current data of the power input and the current data of the load in real time. Among them, the three-phase current data of the power input is the input current data of the inverter, and the current data of the load is the output current data of the inverter.

[0065] In this embodiment, when collecting three-phase current data and load current data, the collection time interval is 1 millisecond. The value of the collection time interval is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0066] Step 2: Determine the abnormal value of the input current data based on the position changes of the peaks and troughs of the input current data of the inverter and the high-frequency noise characteristics; determine the abnormal degree of the output current by analyzing the difference in the abnormal values ​​between the input and output current data, and the degree of local mutation of the output current waveform; determine the impact index based on the difference in output current data in different time periods and the degree of abnormality.

[0067] The DTC of ABB inverter has the advantages of simple structure and fast response, but it also has the problems of large flux and torque pulsation and non-constant inverter switching frequency. To address this problem, the present application uses a sliding film controller to replace the two hysteresis regulators in the traditional DTC, replaces the switching function in the sliding film controller with a continuous function, and sets it as a power approaching law. By adjusting the power parameter in the power approaching law, the switching rate of the control signal is changed, the jitter is reduced, and the control accuracy of the inverter is improved. The size of the power parameter indirectly affects the control effect of the inverter. Specifically, when the power parameter is too large, it can increase the approach speed of the system state to the sliding surface, but it may lead to poor suppression of jitter; when the power parameter is too small, the ability to suppress jitter is relatively good, but the approach speed will slow down. Therefore, according to the current change state at both ends of the power supply and load of the inverter, the power parameter is optimized to obtain a better control effect. Among them, the power approaching law is a well-known technology and will not be repeated in this application.

[0068] Step 2.1, taking each preset time length as a time period, based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input current and output current in time series, and combined with the significance of the high-frequency signal of the input and output current data in the frequency domain, determine the abnormal values ​​of the input and output current data in each time period.

[0069] The power parameter is adjusted once for each preset time length, and each preset time length is regarded as a time period.

[0070] In this embodiment, the value of the preset time length is 5 seconds. The value of the preset time length is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0071] Taking the i-th time period as an example, first, the input current of the inverter is analyzed. The input current is alternating current, which is first converted into direct current through a rectifier during the frequency conversion process. However, unstable power supply may cause irregular current fluctuations, thereby interfering with the subsequent frequency conversion process. The unstable current input of the power supply is reflected in the abnormal jumps of the peak and trough positions of the AC power, the instability of the difference between the peak and the trough, and the possible existence of current high-frequency noise. Therefore, the peak and valley value detection is performed on the input current data in the i-th time period, that is, the peak and valley value detection is performed on the three-phase current data. The schematic diagram of current data peak extraction is shown in the figure. Figure 3 As shown in the figure, the horizontal axis is time, the unit is s, and the vertical axis is input current, the unit is A.

[0072] In this embodiment, the findpeaks function of MATLAB is used to detect the peak value of the input current data. In the findpeaks function, the minimum distance between peaks is set to 0.012 seconds to reduce the interference of high-frequency noise on peak extraction and avoid some abnormal values ​​from being identified as peaks. When detecting the valley value of the input current data in the i-th time period, the input of the findpeaks function is the negative value of the input current data, and the output peak value is the absolute value of the valley value of the input current data. As other implementation methods, on the basis of being able to detect the peak and valley values ​​of the input current data, the implementer can use other existing technologies to detect the peak and valley values ​​of the input current data, such as the peak and valley detection algorithm and the extreme point detection algorithm, and this application does not impose any special restrictions.

[0073] Since the waveform of the input current data floats up and down on both sides of the horizontal axis under normal stability, the difference between the absolute value of the peak value and the valley value of the input current data is small, so all the peak values ​​and valley values ​​detected are arranged in time sequence to form a peak-valley sequence. In the peak-valley sequence, the peak value and the valley value appear alternately. The difference between each data in the peak-valley sequence and its adjacent previous data is calculated respectively, which is recorded as the forward difference; the difference between each data and its adjacent next data is recorded as the backward difference; the mean of the forward difference and the backward difference of each data is calculated, which is recorded as the phase difference mean, and the cumulative sum of the phase difference mean of all data in the peak-valley sequence is used as the difference between the peak value and the valley value. It should be noted that for the first data and the last data in the peak-valley sequence, only the difference between the first data and its adjacent next data is calculated, and only the difference between the last data and its adjacent previous data is calculated. The larger the difference value obtained, the greater the degree of up and down jump of the AC input to the inverter.

[0074] In this embodiment, the difference between the data in the peak and valley sequence is the absolute value of the difference. As other implementation methods, based on the measurable difference between the data in the peak and valley sequence, the implementer can use other calculation methods for measurement, such as ratio, square of difference, etc., and this application does not impose any special restrictions.

[0075] Furthermore, the autocorrelation function is used to calculate the autocorrelation coefficient of the peak-valley sequence at each time delay, and the average of the absolute values ​​of the autocorrelation coefficients of the peak-valley sequence at all time delays is recorded as the autocorrelation mean; the smaller the autocorrelation mean, the less regular the occurrence time of the peak and valley values ​​in the input current data. Among them, the value range of the time delay is [0, N-1], and N is the length of the peak-valley sequence.

[0076] If the input current is more unstable, the high-frequency signals in the spectrum diagram of the input current will increase significantly, and these high-frequency signals are noise. In order to further obtain the characteristics of high-frequency noise, the discrete Fourier transform technology is used to obtain the spectrum diagram of the input current data in the i-th time period. The median of the frequency in the spectrum diagram is counted, and the ratio of the sum of the amplitudes of all frequencies greater than the median in the spectrum diagram to the sum of the amplitudes of all frequencies in the spectrum diagram is taken as the significance of the high-frequency signal of the input current data in the i-th time period; the larger the value of the high-frequency signal significance, the more high-frequency noise there is in the input current in this time period. Among them, the discrete Fourier transform technology is a well-known technology and will not be repeated in this application.

[0077] Based on the above analysis, based on the difference value, the autocorrelation mean and the high-frequency signal significance of each time period, the abnormal value of the input current data in each time period is determined, and the expression is:

[0078] ; In the formula, represents the abnormal value of the input current data in the i-th time period; represents the difference between the peak value and the valley value of the input current data in the i-th time period; Indicates the significance of high-frequency signals of input current data in the i-th time period; It represents the autocorrelation mean of the peak-to-valley sequence in the i-th time period; α represents a preset value greater than 0, which is used to avoid the denominator being 0. The value of α is preset manually and can be set by the implementer. In this embodiment, the value of α is 0.1.

[0079] It should be noted that: The larger the value is, the greater the fluctuation characteristics of the input current will be during the inverter control process, and the more likely it is to aggravate the chattering phenomenon during the inverter control process. The flow chart for determining the abnormal value of the input current data is as follows: Figure 4 shown.

[0080] In the frequency converter, AC power is converted into DC power, and then converted into AC power of various frequencies through an inverter. During the inverter conversion process, it may be affected by electromagnetic interference, causing the output AC power to have unstable characteristics similar to the input current.

[0081] For the output current data in the i-th time period, the same calculation method as the abnormal value of the input current data in the i-th time period is used to calculate the abnormal value of the output current data in the i-th time period; the larger the abnormal value, the more unstable the output current.

[0082] Step 2.2, based on the difference in abnormal values ​​between the input current data and the output current data in each time period, and the degree of mutation of the output current data in each time period, determine the abnormal degree of the output current data in each time period.

[0083] During the inverter conversion process, it may be affected by electromagnetic interference, resulting in local mutations in the output AC power.

[0084] The stable approximate relationship between the input and output currents of the inverter is reflected by the abnormal values ​​of the input current data and the output current data in the i-th time period. When the inverter is in poor operating condition, the abnormal values ​​of the input current data and the output current data in the i-th time period are both large, or the difference between the abnormal values ​​of the input current data and the output current data in the i-th time period is large. Therefore, the average of the abnormal values ​​of the input current data and the output current data in the i-th time period and the fusion result of the difference between the two are used as the difference value of the stable state between the input and output currents in the i-th time period. The larger the difference value obtained, the worse the stability of the input and output currents of the inverter.

[0085] In this embodiment, the difference between the outliers is the absolute value of the difference. As other implementation methods, based on the difference between the measurable outliers, the implementer can use other calculation methods for measurement, such as ratio, square of the difference, etc., and this application does not impose any special restrictions.

[0086] It should be understood that fusion refers to combining multiple independent variables in a way that enhances the overall effect, such as an additive relationship, a multiplicative relationship, etc. The implementer may limit it according to the actual situation, and this application does not impose any special restrictions.

[0087] In this embodiment, the average of the abnormal value of the input current data and the abnormal value of the output current data in the i-th time period and the sum of the differences between the two are used as the difference value of the stable state between the input and output currents in the i-th time period.

[0088] In another embodiment, the product of the average of the abnormal value of the input current data and the abnormal value of the output current data in the i-th time period and the difference between the two is used as the difference value of the stable state between the input and output currents in the i-th time period.

[0089] In addition, under the influence of electromagnetic interference, the output current has local mutations in the waveform. Therefore, a mutation point detection algorithm is used to detect mutation points in the output current data in the i-th time period to obtain the statistics corresponding to each mutation point. The accumulated value of the statistics corresponding to all mutation points is taken as the mutation value of the output current data in the i-th time period. The larger the mutation value obtained, the greater the degree of local mutation of the inverter's output current.

[0090] Combining the distinguishing characteristics of the stable state between the input and output currents in each time period and the local mutation characteristics of the output current, the abnormal degree of the output current data in each time period is determined. The expression is:

[0091] ; In the formula, Indicates the abnormality of the output current data in the i-th time period; Indicates the difference between the input and output currents in the steady state during the i-th time period; Indicates the sudden change value of the output current data in the i-th time period. The larger the value is, the greater the abnormality of the output current waveform is. The flow chart for determining the abnormality of the output current data is as follows: Figure 5 shown.

[0092] Step 2.3, based on the abnormality degree in each time period and its adjacent time period, and combined with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference during the inverter control process in each time period.

[0093] Since the inverter needs to ensure the accuracy of current control over a long period of time, the change characteristics of the output current data between different time periods and the abnormality of the current waveform are further analyzed. The more inconsistent the output current data of the inverter in adjacent time periods is, and the greater the abnormality of the current data is, the more susceptible the control of the inverter is to interference.

[0094] Based on the above analysis, all output current data in each time period are arranged in time series to form each output current data sequence, and the distance between the output current data sequence of the i-th time period and its adjacent previous time period is calculated. The larger the distance, the more inconsistent the change characteristics of the current data between the two adjacent time periods.

[0095] In this embodiment, the distance between the output current data sequences is the SBD (Shape Based Distance) distance. As other implementation methods, on the basis of being able to measure the distance between the output current data sequences, the implementer may adopt other existing technologies to measure the distance between the output current data sequences, such as Euclidean distance, Manhattan distance, etc., and this application does not impose any special restrictions.

[0096] Based on the abnormal degree of the output current data in each time period and its adjacent time period, and combined with the difference in the output current data between each time period and its adjacent time period, the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period is determined. The expression is:

[0097] ; In the formula, It represents the influence index of power supply fluctuation and electromagnetic interference during the inverter control process in the i-th time period; Represents the distance between the output current data sequence of the i-th time period and its adjacent previous time period; It represents the mean value of the abnormality of the output current data in the i-th time period and its adjacent time periods.

[0098] It should be noted that: The larger the value, the greater the impact of power fluctuation and electromagnetic interference on the inverter, and the power parameters of the power approaching law in the sliding film controller need to be adjusted in time. Figure 6 shown.

[0099] Step 3: Based on the influence index in the current time period, determine the power parameter of the power reaching law in the synovial controller in the inverter in the next time period.

[0100] The influence index of power supply fluctuation and electromagnetic interference during the inverter control process in the current time period reflects the influence degree of power supply fluctuation and electromagnetic interference on the inverter control during the current time period. If the influence index is larger, it means that the suppression effect of the vibration during the inverter control process is worse, and the output current is more affected. At this time, it is necessary to reduce the power parameter in the power reaching law to improve the suppression effect of the vibration; on the contrary, if the influence index is smaller, the power parameter in the power reaching law can be appropriately increased to increase the approach speed of the system state to the sliding surface and improve the dynamic response of the system.

[0101] The value range of the power parameter is (0,1), and the specific calculation formula of the power parameter is: ; In the formula, Q represents the power parameter of the power approaching law in the sliding film controller in the inverter in the next time period; X represents the normalized result of the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in the current time period. This embodiment uses the Tanh activation function to normalize the influence index.

[0102] For the initial two time periods, the power parameter is the preset value. Starting from the third time period, the power parameter calculated in the previous time period is used as the power parameter of the power approaching law in the sliding film control in the current time period, which improves the vibration suppression effect of the sliding film controller while maintaining a good approaching speed. The inverter output current curve before optimization is shown in the figure below: Figure 7 As shown in the figure, the horizontal axis is time, the unit is s, the vertical axis is output current, the unit is A, and the curve is the output current curve before the power parameter is optimized. The inverter output current curve after optimization is as follows Figure 8 As shown in the figure, the horizontal axis is time, the unit is s, the vertical axis is output current, the unit is A, and the curve is the output current curve after the power parameters are optimized. Figure 7 and Figure 8 It can be seen that after the power parameters are optimized, the vibration suppression effect during the inverter control process is better, which leads to a smaller degree of impact on the output current.

[0103] In this embodiment, the preset value is 0.5. The preset value is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0104] Based on the same inventive concept as the above method, the embodiment of the present application further provides a frequency converter control device, including:

[0105] Current acquisition module, used to collect the input current data and output current data of the inverter in real time;

[0106] The interference analysis module is used to take each preset time length as a time period, and determine the abnormal values ​​of the input and output current data in each time period based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input and output currents in the time series, and combined with the significance of the high-frequency signals of the input and output current data in the frequency domain;

[0107] Determine the abnormality degree of the output current data in each time period based on the difference in abnormal values ​​between the input current data and the output current data in each time period and the degree of mutation of the output current data in each time period;

[0108] Based on the abnormality degree in each time period and its adjacent time period, and in combination with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period;

[0109] The control parameter determination module is used to determine the power parameter of the power reaching law in the synovial controller in the inverter in the next time period based on the influence index in the current time period.

[0110] Based on the same inventive concept as the above method, an embodiment of the present application also provides a frequency converter control system, including a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the steps of any one of the above-mentioned frequency converter control methods are implemented.

[0111] In summary, the present application determines the abnormal values ​​of the input and output current data in each time period based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input and output current in the time series, and combines the significance of the high-frequency signals of the input and output current data in the frequency domain, and fully considers multiple aspects of the irregular fluctuation characteristics of the input and output current data, thereby improving the accuracy of the fluctuation characteristic analysis of the input and output current data;

[0112] Furthermore, based on the difference in abnormal values ​​between the input current data and the output current data in each time period, and the degree of mutation of the output current data in each time period, the degree of abnormality of the output current data in each time period is determined; the difference in fluctuation characteristics between the input current and the output current, and the mutation of the output current itself are comprehensively analyzed, thereby improving the accuracy of the analysis of the degree of abnormality of the output current data;

[0113] Furthermore, based on the abnormality degree in each time period and its adjacent time period, and combined with the difference in output current data between each time period and its adjacent time period, the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period is determined; the difference in the abnormality degree of output current between different time periods is combined to improve the accuracy of analyzing the influence degree of power supply fluctuation and electromagnetic interference on the inverter;

[0114] Based on the influence index in the current time period, the power parameters of the power reaching law in the sliding film controller in the inverter in the next time period are determined; according to the severity of the jitter phenomenon caused by power supply fluctuations and electromagnetic interference, the power parameters of the power reaching law in the sliding film controller are optimized, which can improve the suppression effect of jitter while ensuring a good approach speed, thereby improving the accuracy of inverter control.

[0115] The flowchart and block diagram in the accompanying drawings show the possible architecture, function and operation of the system, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

[0116] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the basic features of the present application. Therefore, no matter from which point of view, the above embodiments of the present application should be regarded as exemplary and non-restrictive.

Claims

1. A frequency converter control method, characterized in that: The method comprises the following steps: Collect the input current data and output current data of the inverter in real time; Taking each preset time length as a time period, based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input current and output current in the time series, and combining the significance of the high-frequency signal of the input and output current data in the frequency domain, the abnormal values ​​of the input and output current data in each time period are determined respectively; Determine the abnormality degree of the output current data in each time period based on the difference in abnormal values ​​between the input current data and the output current data in each time period and the degree of mutation of the output current data in each time period; Based on the abnormality degree in each time period and its adjacent time period, and in combination with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period; Based on the influence index in the current time period, determining the power parameter of the power reaching law in the synovial controller in the inverter in the next time period; Arrange all peak values ​​and all valley values ​​of the input current data in each time period in time sequence to form a peak-valley sequence; Based on the distribution of the difference between each data and its adjacent data in each peak-valley sequence, the difference between the peak value and the valley value of the input current data in each time period is determined; Calculate the autocorrelation coefficient of each peak-valley sequence at each time delay, and record the average of the absolute values ​​of the autocorrelation coefficients of each peak-valley sequence at all time delays as the autocorrelation mean; Obtaining the median value of the frequency in the frequency spectrum of the input current data in each time period, and taking the ratio of the sum of the amplitudes of all frequencies in each frequency spectrum that are greater than the median value to the sum of the amplitudes of all frequencies in each frequency spectrum as the high-frequency signal significance of the input current data in each time period; The abnormal value is respectively proportional to the difference value and the significance of the high-frequency signal, and inversely proportional to the autocorrelation mean; For the output current data in each time period, the abnormal value of the output current data in each time period is obtained by adopting the same method as that for obtaining the abnormal value of the input current data in each time period.

2. A frequency converter control method as claimed in claim 1, characterized in that: The process of determining the difference value is as follows: The difference between each data in each peak-valley sequence and its previous adjacent data is calculated respectively, recorded as the forward difference; the difference between each data and its subsequent adjacent data is recorded as the backward difference, and the mean of the forward difference and the backward difference of each data is calculated, recorded as the phase difference mean; The cumulative sum of the phase difference mean values ​​of all data in each peak-valley sequence is taken as the difference value between the peak value and the valley value of the input current data in each time period.

3. A frequency converter control method as claimed in claim 1, characterized in that: The expression of the abnormal value is: ; In the formula, represents the abnormal value of the input current data in the i-th time period; It represents the difference between the peak value and the valley value of the input current data in the i-th time period; Indicates the significance of high-frequency signals of input current data in the i-th time period; Represents the autocorrelation mean of the peak-to-valley sequence in the i-th time period; α represents a preset value greater than 0.

4. A frequency converter control method as claimed in claim 1, characterized in that: The process of determining the abnormality degree is as follows: Calculate the average value of the abnormal value of the input current data and the abnormal value of the output current data in each time period; The difference between the abnormal values ​​of the input current data and the output current data in each time period and the fusion result of the average value are used as the difference value of the stable state between the input and output currents in each time period; A mutation point detection algorithm is used to obtain the statistics corresponding to each mutation point in the output current data in each time period, and the accumulated value of the statistics corresponding to all mutation points in the output current data in each time period is used as the mutation value of the output current data in each time period; The abnormality degree of the output current data in each time period is obtained by combining the difference value and the mutation value.

5. A frequency converter control method as claimed in claim 4, characterized in that: The abnormality degree is the product of the distinction value and the mutation value.

6. A frequency converter control method as claimed in claim 1, characterized in that: The process of determining the impact index is as follows: Arrange all output current data in each time period in time sequence to form each output current data sequence; Calculate the distance between each time period and the output current data sequence of its adjacent time period; The influence index is positively correlated with the distance, the abnormality level in each time period, and the abnormality level in the adjacent time period of each time period.

7. A frequency converter control method as claimed in claim 1, characterized in that: The calculation formula of the power parameter is: ; In the formula, Q represents the power parameter of the power reaching law in the sliding film controller in the inverter in the next time period; X represents the normalized result of the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in the current time period.

8. A frequency converter control device, implementing the method as claimed in claim 1, characterized in that: The device comprises: Current acquisition module, used to collect the input current data and output current data of the inverter in real time; The interference analysis module is used to take each preset time length as a time period, and determine the abnormal values ​​of the input and output current data in each time period based on the fluctuation of all peak values ​​and all valley values ​​of the input and output current data in each time period, as well as the autocorrelation of the input and output currents in the time series, and combined with the significance of the high-frequency signals of the input and output current data in the frequency domain; Determine the abnormality degree of the output current data in each time period based on the difference in abnormal values ​​between the input current data and the output current data in each time period and the degree of mutation of the output current data in each time period; Based on the abnormality degree in each time period and its adjacent time period, and in combination with the difference in output current data between each time period and its adjacent time period, determine the influence index of power supply fluctuation and electromagnetic interference in the inverter control process in each time period; The control parameter determination module is used to determine the power parameter of the power reaching law in the synovial controller in the inverter in the next time period based on the influence index in the current time period.

9. A frequency converter 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 frequency converter control method as described in any one of claims 1 to 7 are implemented.

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