Online power monitoring method, system and device for PTC heater

Abstract

The present invention relates to the technical field of power monitoring, and particularly to an online power monitoring method, system and device for a PTC heater. The method determines the instability degree of the electrical parameter environment through the unstable conditions of the current current and the historical current approaching the Curie point temperature; obtains the change degree of the heat dissipation condition through the trend fluctuation of the temperature deviation in time series; determines the temperature deviation period through the deviation from the gear temperature, and evaluates the environmental heat dissipation disorder degree according to the difference between the temperature deviation segments; obtains the monitoring sensitivity through the electrical parameter environment stability, the heat dissipation condition change degree and the environmental heat dissipation disorder degree, and adjusts the power monitoring range for monitoring. By analyzing the influence of the heat dissipation environment on the PTC heater and adjusting the power quantization range with different monitoring degrees, the present invention improves the monitoring accuracy in different environments and makes the monitoring results more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of power monitoring, and particularly to an online power monitoring method, system and device for a PTC heater. Background Art

[0002] A PTC heating element, also known as a PTC heater, is composed of a PTC ceramic heating unit and an aluminum pipe fitting. Such a PTC heating element has the advantages of low thermal resistance and high-efficiency heat exchange, and is an electric heating element with an automatic constant temperature function and remarkable energy-saving effect. Its most prominent advantage lies in its safety performance. However, the PTC material has a self-limiting temperature characteristic. If the power supply is abnormally too high, safety problems may still occur. Therefore, through online monitoring, the input power can be adjusted in time to reduce energy consumption, and abnormal input power or excessive power consumption can be detected immediately.

[0003] When conventionally monitoring the power of a PTC heater online, a power change range is usually preset for monitoring. When the power change of the PTC heater exceeds this range, its power is considered abnormal. However, in many application scenarios, the heat dissipation environment of the PTC heater will change greatly, which will cause a large change between the actual temperature of the PTC heater and the preset gear temperature. When the influence of environmental factors is high, the power change value caused by the self-regulation characteristic of the PTC heater may also exceed the range, resulting in errors in the monitoring results and low monitoring accuracy under complex environmental changes. Summary of the Invention

[0004] In order to solve the technical problem that when the influence of environmental factors is high in the prior art, the power change value caused by the self-regulation characteristic of the PTC heater may also exceed the range, resulting in errors in the monitoring results and low monitoring accuracy under complex environmental changes, the purpose of the present invention is to provide an online power monitoring method, system and device for a PTC heater, and the specific technical solutions adopted are as follows:

[0005] The present invention provides an online power monitoring method for a PTC heater, and the method includes:

[0006] Collect the sequential current sequence during the heating process, the output temperature and the ambient temperature of the PTC heater at each moment, and obtain the historical current sequence of heating to the current preset gear temperature;

[0007] Obtain the electrical parameter environmental instability degree of the sequential current sequence according to the instability of the current deviation between the sequential current sequence and the historical current sequence near the Curie point temperature;

[0008] Obtain the heat dissipation condition change degree of the sequential current sequence according to the trend fluctuation of the deviation change between the output temperature and the ambient temperature corresponding to the sequential current sequence in the sequence.

[0009] Determine the temperature deviation segment in the time-sequence current sequence according to the deviation degree between the output temperature and the currently preset gear temperature in the corresponding time sequence of the time-sequence current sequence; analyze the differences in temperature deviation, current change, and time period duration trend among different temperature deviation segments in the time-sequence current sequence to obtain the environmental heat dissipation disorder degree of the time-sequence current sequence;

[0010] Combine the electrical parameter environmental instability degree, heat dissipation condition change degree, and environmental heat dissipation disorder degree of the time-sequence current to obtain the monitoring sensitivity; adjust the monitoring range of power monitoring based on the monitoring sensitivity for monitoring.

[0011] Further, the method for obtaining the electrical parameter environmental instability degree includes:

[0012] For any current sequence, obtain the current curve of the current sequence through curve fitting; obtain the slope at each moment in the current curve, and use the moment corresponding to the maximum slope as the change point moment;

[0013] Take the numerical difference between the current data at each moment in the current sequence and the current data on the circuit curve as the fitting deviation value at each moment in the current sequence;

[0014] Normalize the time interval between each moment and the change point moment to obtain the stability weight at each moment;

[0015] Use the stability weight at each moment as the weight to weight all fitting deviation values, and then calculate the standard deviation to obtain the instability factor of the current sequence;

[0016] After calculating the difference in instability factors between the time-sequence current sequence and each historical current sequence, calculate the mean of all differences to obtain the electrical parameter environmental instability degree of the time-sequence current sequence.

[0017] Further, the method for obtaining the heat dissipation condition change degree includes:

[0018] Take the numerical difference between the output temperature and the environmental temperature at each moment corresponding to the time-sequence current sequence as the heat loss value at each moment; arrange the heat loss values in chronological order to obtain the heat loss sequence;

[0019] Obtain the principal component direction of the heat loss sequence through PCA principal component analysis; normalize the angle between the principal component direction and the horizontal straight line as the heat dissipation condition change degree of the time-sequence current sequence.

[0020] Further, the method for determining the temperature deviation segment includes:

[0021] Normalize the numerical difference between the output temperature at each moment in the time-series current sequence and the current preset gear temperature to obtain the deviation value at each moment; regard the moment when the deviation value is greater than the preset deviation threshold as the deviation temperature moment;

[0022] Merge the continuously distributed deviation temperature moments in the time-series current sequence to obtain the temperature deviation segment.

[0023] Further, the method for obtaining the environmental heat dissipation disorder degree includes:

[0024] Regard every two different temperature deviation segments in the moment current sequence as a deviation time period group;

[0025] For any deviation time period group, combine the difference in the maximum current change between the temperature deviation segments in this deviation time period group and the difference between the maximum deviation values to obtain the change deviation index of this deviation time period group;

[0026] According to the time period duration difference and the similarity of the deviation value distribution trend between the temperature deviation segments in this time period deviation group, obtain the time series deviation index of this deviation time period group;

[0027] Combine the change deviation index and the time series deviation index of each deviation time period group to obtain the environmental heat dissipation disorder degree of the time-series current sequence.

[0028] Further, the method for obtaining the time series deviation index includes:

[0029] Normalize the difference in the time period length between the two temperature deviation segments in this deviation time period group to obtain the duration index of this deviation time period group;

[0030] Regard the sequence in which the deviation values on each temperature deviation segment in this deviation time period group are distributed in time sequence as the time period deviation sequence of each temperature deviation segment;

[0031] Use the DTW matching algorithm for the time period deviation sequences of the two temperature deviation segments in this deviation time period group to obtain the DTW value of this deviation time period group; perform negative correlation mapping and normalization processing on the DTW value of this deviation time period group to obtain the trend weight of this deviation time period group;

[0032] Take the product of the trend weight and the duration index of this deviation time period group as the time series deviation index of this deviation time period group.

[0033] Further, the method for obtaining the monitoring sensitivity includes:

[0034] Perform weighted summation on the heat dissipation condition change degree of the time-series current and the environmental heat dissipation disorder degree to obtain the instability degree of the heat dissipation environment of the time-series current;

[0035] Negatively correlate and normalize the product of the instability degree of the heat dissipation environment of the sequential current and the instability degree of the electrical parameter environment to obtain the monitoring sensitivity.

[0036] Further, the monitoring based on adjusting the power monitoring range according to the monitoring sensitivity includes:

[0037] Multiply the monitoring sensitivity by the preset adjustment range as the adjustment range; subtract the adjustment range from the preset maximum range as the change range.

[0038] If the power of the PTC heater in the sequential current sequence is outside the change range of the preset standard power, the monitoring result is abnormal.

[0039] The present invention also provides a power online monitoring system for a PTC heater, including:

[0040] A data acquisition module, configured to collect the sequential current sequence during the heating process, the output temperature and the ambient temperature of the PTC heater at each moment, and obtain the historical current sequence of heating to the current preset gear temperature.

[0041] An electrical parameter environment analysis module, configured to obtain the instability degree of the electrical parameter environment of the sequential current sequence according to the instability of the current deviation between the sequential current sequence and the historical current sequence near the Curie point temperature.

[0042] A heat dissipation condition change analysis module, configured to obtain the change degree of the heat dissipation condition of the sequential current sequence according to the trend fluctuation of the deviation between the output temperature and the ambient temperature corresponding to the sequential current sequence.

[0043] An environmental heat dissipation disorder analysis module, configured to determine the temperature deviation segment in the sequential current sequence through the deviation degree between the output temperature corresponding to the sequential current sequence and the current preset gear temperature; analyze the differences in temperature deviation, current change, and time period duration trend among different temperature deviation segments in the sequential current sequence to obtain the environmental heat dissipation disorder degree of the sequential current sequence.

[0044] An adjustment monitoring module, configured to combine the instability degree of the electrical parameter environment, the change degree of the heat dissipation condition, and the environmental heat dissipation disorder degree of the sequential current to obtain the monitoring sensitivity; monitor based on adjusting the power monitoring range according to the monitoring sensitivity.

[0045] The present invention also provides a power online monitoring device for a PTC heater, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of any one of the above-mentioned power online monitoring methods for a PTC heater.

[0046] The present invention has the following beneficial effects:

[0047] Based on the instability of the current state of the current and historical current near the Curie point temperature, the present invention determines the instability of the electrical parameter environment of the PTC heater at its own heating level. By the characteristic that the PTC heater has a Curie temperature point and the current is limited when approaching the Curie temperature point, the present invention expands the performance of the electrical parameters during the heating process, improving the accuracy of analyzing the electrical parameter environment. The present invention reflects heat loss through the temperature deviation in time series, and reflects the possible influence of environmental heat dissipation according to the trend fluctuation of the deviation, obtaining the degree of change in heat dissipation conditions. Considering the influence of the unstable heat dissipation environment on the actual adjustment judgment as a whole, it provides a data basis for subsequent environmental impact analysis. Under the influence of complex environmental factors, the instability of the environmental heat dissipation change results in a higher feedback of the current change with a time delay effect. By determining the time period with a higher feedback based on the deviation from the gear temperature, and evaluating the degree of environmental heat dissipation disorder according to the differences between the deviation segments, it reduces the errors caused by complex environmental factors during subsequent monitoring. Finally, by comprehensively adjusting the monitoring sensitivity based on the electrical parameter environment stability, the degree of change in heat dissipation conditions, and the degree of environmental heat dissipation disorder, the range of power monitoring is made more reliable. The present invention adjusts the monitoring degree of the power quantization range of the PTC heater affected by the heat dissipation environment, improving the accuracy of monitoring in different environments and making the monitoring results more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Figure 1 It is a flowchart of a method for online power monitoring of a PTC heater provided by an embodiment of the present invention;

[0050] Figure 2 It is a flowchart of a method for obtaining the degree of environmental heat dissipation disorder provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with the drawings and preferred embodiments, details the specific implementation manners, structures, features, and effects of a method, system, and device for online power monitoring of a PTC heater according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs.

[0053] The following specifically describes the specific solutions of a power on-line monitoring method, system and device for a PTC heater provided by the present invention in conjunction with the accompanying drawings.

[0054] Example 1:

[0055] Please refer to Figure 1 , which shows a flowchart of a power on-line monitoring method for a PTC heater provided by an embodiment of the present invention. The method includes the following steps:

[0056] S1: Collect the time-series current sequence during the heating process, the output temperature and the ambient temperature of the PTC heater at each moment, and obtain the historical current sequence when heating to the current preset gear temperature.

[0057] The working principle of the PTC heater is mainly as follows: After selecting the gear temperature or preset temperature, current is provided to make the heater start to heat up. As the temperature rises and gradually approaches the Curie point temperature, the resistance will increase rapidly, and the heating rate will accelerate. At this time, the current needs to be reduced to avoid further heating. At this time, the resistance will stabilize at a value to ensure that the heater is at the preset gear temperature.

[0058] The above are all ideal situations. When the environment where the PTC heater is located changes, such as when the temperature and wind speed change, it usually causes the actual temperature of the heater to change, the resistance of the heater itself to change accordingly, and then the output current to change synchronously to ensure that the actual operating temperature of the heater remains at the preset gear or preset value.

[0059] However, for a PTC heater, since its actual resistance changes in real time with temperature, it is affected by current and voltage to a certain extent. Therefore, the influence between these parameters exists mutually. However, in actual scenarios, the current and voltage applied to the PTC are unstable or the parameters are inaccurate. At this time, in order to determine whether the power of the current PTC heater is within the safe and normal range, it is inaccurate to rely solely on the actual monitoring results.

[0060] In the embodiments of the present invention, the length of five minutes in the time series before the current moment is used as a sequence length. The real-time current input to the PTC heater is obtained through a current sensor to obtain a time-series current sequence. The temperature sensor is arranged on the surface or outside of the device where the PTC heater is located to obtain the output temperature of the current temperature sensor, and at the same time, the temperature monitoring result of the current scenario used by the heater, that is, the ambient temperature, is obtained. For example, if the current scenario used by the PTC heater is a vehicle heater, the two temperature data obtained at this time are the air outlet temperature and the seat or in-vehicle temperature respectively; if the scenario used by the PTC heater is air-conditioning heating, the indoor temperature and the air outlet temperature are obtained through the home system at the same time. That is, essentially, the current surface output temperature of the PTC heater and the ambient temperature of the actual object of action need to be obtained. The acquisition frequency can be set to once per second, and the specific implementer of the acquisition can adjust it according to the specific implementation situation, which is not limited here.

[0061] When the PTC heater is at the same gear temperature or preset temperature, its heating process starting from 0 is theoretically exactly the same in theory. However, under different requirements, there are obvious differences in its output stability during the heating process. Therefore, in the embodiments of the present invention, the historical current sequence of the current preset gear temperature is obtained. The historical current sequence is a sequence composed of current time-series data during the process of the PTC heater heating from 0 to the current required preset gear temperature in the historical time series.

[0062] For the PTC heater, since its actual resistance changes in real time with temperature, it is affected by current and voltage to a certain extent. In the actual scenario, the current applied to the PTC may be unstable or the parameters may be inaccurate. At this time, in order to determine whether the power of the current PTC heater is within the safe and normal range, it is inaccurate to rely solely on the actual monitoring results, and it is necessary to further evaluate the environmental quality and adjust the sensitivity of the monitoring.

[0063] S2: According to the instability of the current deviation between the time-series current sequence and the historical current sequence near the Curie point temperature, obtain the electrical parameter environmental instability degree of the time-series current sequence.

[0064] The PTC heater usually uses a material with a positive temperature coefficient effect. When the temperature of this material rises, its resistance will increase with the increase of temperature, and when it reaches the Curie point temperature, the change in resistance is very drastic. The Curie point temperature of this material is a key parameter, usually determined by the material properties and is a fixed value. The Curie point temperature refers to the critical temperature of some materials, such as ferromagnetic materials. Below this temperature, the material retains its magnetism; while above this temperature, the material loses its magnetism. For the PTC heater, the Curie point temperature refers to the temperature at which the resistance of the material increases sharply when the temperature of the material reaches a certain critical value.

[0065] When the temperature of the PTC heater approaches its Curie point, the increase in the resistance of the material causes a decrease in the current, thereby suppressing the temperature rise of the heater, preventing the temperature from continuing to rise, and playing a role in self-regulation and overheat protection. This characteristic is the basis for the stable operation of the PTC heater, and it will amplify the performance of current fluctuations during different heating processes, making the differences between different heating processes more significant. Therefore, further through the instability of the current deviation between the current sequence and the historical current sequence at the temperature approaching the Curie point, the sensitivity of the relative change of the electrical parameters of the heater itself during operation is reflected.

[0066] Preferably, in the embodiment of the present invention, the method for obtaining the instability degree of the electrical parameter environment includes:

[0067] First, for any current sequence, the current curve of the current sequence is obtained through curve fitting. In the embodiment of the present invention, the time series data in the current sequence can be fitted and smoothed by the least squares method. The slope at each moment of the current curve is obtained, and the moment corresponding to the maximum slope is used as the change point moment. Since the temperature of the PTC heater gradually approaches its own Curie point temperature, the resistance changes relatively fast, and the corresponding change in current is also relatively drastic.

[0068] Furthermore, the numerical difference between the current data at each moment in the current sequence and the current data on the circuit curve is used as the fitting deviation value at each moment in the current sequence. The instability of the actual current is reflected through the fitting deviation.

[0069] The time interval between each moment and the change point moment is normalized to obtain the stability weight at each moment. The weight is set according to the approach to the Curie point temperature. The closer the moment is to the change point, the higher the interference to the current data itself is considered, and the more unstable it is to participate in the analysis. It should be noted that the normalization process is a well-known technical means in the art, and methods such as linear normalization or standard normalization can be used, which are not limited herein.

[0070] When the fitting deviation value is more disordered and the size difference is more dispersed, it indicates that the electrical parameter data applied to the heater during the heating process is more unstable, resulting in an increase in current fluctuations. Therefore, further, the stability weight at each moment is used as a weight to weight all the fitting deviation values, and the standard deviation is calculated to obtain the instability factor of the current sequence. Through the calculation of the weighted standard deviation, the disorder degree of the deviation value is characterized, and the instability degree of the current sequence is reflected.

[0071] When the electrical parameter environment of the PTC heater is unstable, such as when the applied voltage environment is unstable, it will cause the heating situation during the heating process to be unstable, and then cause the current to be unstable. Therefore, the instability of the current electrical parameter environment needs to be compared with the historical electrical parameter environment to analyze the sensitive impact of the electrical parameter environment on the monitoring.

[0072] Finally, after calculating the differences in instability factors between the time-series current sequence and each historical current sequence, the mean value of all the differences is calculated to obtain the instability degree of the electrical parameter environment of the time-series current sequence. The greater the overall difference in the instability between the time-series current sequence and the historical current sequences, the higher the relative instability degree of the current electrical parameter environment.

[0073] Thus, the analysis of the electrical parameter environment during the current heating process is completed.

[0074] S3: According to the trend fluctuation of the deviation change between the output temperature and the ambient temperature corresponding to the time-series current sequence in time sequence, obtain the change degree of the heat dissipation condition of the time-series current sequence.

[0075] Furthermore, for a PTC heater, when it reaches the stable preset gear, due to heat dissipation in the current working environment, when the heat dissipation condition is unstable, it will correspondingly affect the actual temperature of the PTC heater. When the ambient temperature drops, the corresponding resistance needs to change, thereby affecting the actual current magnitude. Therefore, it is necessary to conduct a preliminary analysis on whether the heat dissipation condition of the current environment is stable.

[0076] Preferably, in the embodiment of the present invention, the method for obtaining the change degree of the heat dissipation condition includes:

[0077] Take the numerical difference between the output temperature and the ambient temperature at each moment corresponding to the time-series current sequence as the heat loss value at each moment, arrange all the heat loss values in time sequence to obtain a heat loss sequence, which reflects the external heat loss situation in time sequence during the heating process of the current PTC heater.

[0078] Obtain the principal component direction of the heat loss sequence through PCA principal component analysis, which reflects the change trend of the temperature loss. For the heat loss degree sequence, the principal component direction represents the main pattern of the sequence changing with time, that is, the principal component direction represents the dominant trend of the heater temperature change.

[0079] If the direction of the principal component is very close to the horizontal line, it indicates that the temperature change of the heater is stable and the ambient heat dissipation condition is relatively stable. If the direction of the principal component deviates greatly from the horizontal line, it indicates that the trend of the temperature change is greatly affected by external factors such as wind speed and humidity changes, resulting in unstable temperature change and changed heat dissipation conditions.

[0080] Therefore, normalize the angle between the principal component direction and the horizontal straight line as the change degree of the heat dissipation condition of the time-series current sequence. The greater the change degree of the heat dissipation condition, the greater the change in the external heat dissipation condition, which will affect the temperature of the PTC heater itself and cause synchronous changes in resistance and current. In the embodiment of the present invention, the angle can be quantified by the sine function of the angle, which is not limited herein.

[0081] S4: Determine the temperature deviation segments in the time-sequential current sequence according to the deviation degree between the output temperature and the currently preset gear temperature at corresponding times in the time-sequential current sequence; analyze the differences in temperature deviation, current change, and duration trend among different temperature deviation segments in the time-sequential current sequence to obtain the environmental heat dissipation disorder degree of the time-sequential current sequence.

[0082] After the PTC heater reaches the preset gear temperature, due to the effect of delay, the temperature of the heater itself will change first, and then the resistance will change, thereby causing a change in current. Therefore, it is not sufficient to analyze the complexity of the current heat dissipation environment change based only on the overall change sequence. It is also necessary to further analyze the feedback change of the current when the temperature changes.

[0083] When the temperature of the PTC heater changes due to environmental heat dissipation, its resistance changes. Due to its own constant temperature characteristic, it will adjust the current magnitude and then adjust the heating efficiency to make the temperature return to the preset gear temperature. Therefore, there will be many time periods with obvious temperature deviations in the sequence. First, the time periods can be screened according to the actual temperature deviation situation. In the embodiments of the present invention, the method for obtaining the temperature deviation segments includes:

[0084] First, normalize the numerical difference between the output temperature and the currently preset gear temperature at each moment in the time-sequential current sequence to obtain the deviation value at each moment, which reflects the degree of change affected by the output temperature caused by the environment. The moment with the deviation value greater than the preset deviation threshold is used as the deviation temperature moment, and the moments that are significantly affected and deviated are screened through threshold judgment. In the embodiments of the present invention, the preset deviation threshold is set to 0.5, and the specific value can be adjusted by the implementer according to the implementation situation and is not limited here.

[0085] Then, merge the continuously distributed deviation temperature moments in the time-sequential current sequence to obtain the temperature deviation segments. By adjacent the continuous deviation temperature moments, multiple temperature deviation segments can be screened, reflecting multiple adjustment processes of the heater itself affected by the environment during the heating process of the PTC heater.

[0086] When the electrical parameter environment of the current environment is stable and the environmental heat dissipation conditions are also relatively stable, the temperature deviation caused by the environment and the resulting current change value should also be the same, and the adjustment time should also be close. Therefore, the environmental heat dissipation disorder degree of the current environment where the PTC heater is located can be evaluated based on the differences in temperature deviation, current change, and duration.

[0087] Preferably, in the embodiments of the present invention, for the method for obtaining the environmental heat dissipation disorder degree, please refer to Figure 2 , which shows a flowchart of a method for obtaining the environmental heat dissipation disorder degree provided by an embodiment of the present invention. The method includes the following steps:

[0088] S411: Take every two different temperature deviation segments in the moment current sequence as a deviation time period group. For any deviation time period group, obtain the change deviation index of this deviation time period group by combining the difference in the maximum current change and the difference in the maximum deviation value between the temperature deviation segments in this deviation time period group.

[0089] For the convenience of analyzing the difference between any two temperature deviation segments, group and analyze every two different temperature deviation segments. When the difference in the deviation values caused by the abnormal external heat dissipation environment between the temperature deviation segments in any deviation time period group is greater, and at the same time the difference in the change of the current is greater, it indicates that the influence difference of the current heat dissipation environment on the PTC heater is greater, and at the same time the power change required to adjust back to the preset gear temperature is also greater.

[0090] Analyze from the difference between the temperature deviation segments to reflect the complex change situation of the current heat dissipation environment, rather than the general cyclic phenomenon of heat accumulation around the PTC heater, then heat loss after the power is stable, then the power changes, and then heat accumulation occurs again.

[0091] In the embodiment of the present invention, normalize the difference in the maximum deviation value between the two temperature deviation segments in this deviation time period group to obtain the temperature deviation index of this deviation time period group, which reflects the degree of inconsistency in temperature deviation between time periods. For each temperature deviation segment in this deviation time period group, calculate the numerical difference between the current data at every two adjacent moments in this temperature deviation segment, and take the largest numerical difference as the maximum current change value of this temperature deviation segment, which represents the maximum fluctuation degree of the current on each temperature deviation segment.

[0092] Further normalize the difference in the maximum current change value between the two temperature deviation segments in this deviation time period group to obtain the current change index of this deviation time period group, which reflects the degree of inconsistency in current fluctuation between time periods.

[0093] Finally, take the sum value of the temperature deviation index and the current change index of this deviation time period group as the change deviation index of this deviation time period group, and combine the two difference dimensions to represent the degree of inconsistency between the two temperature deviation segments.

[0094] S412: Obtain the timing deviation index of this deviation time period group according to the time period duration difference and the similarity of the deviation value distribution trend between the temperature deviation segments in this time period deviation group.

[0095] Furthermore, the similarity of the adjustment time between temperature deviation segments can be analyzed. Considering that there are different temperature change trends during the adjustment process, the accuracy of the similarity judgment of the adjustment duration is adjusted through trend analysis. Therefore, in the embodiment of the present invention, first, the difference in the segment lengths between two temperature deviation segments in the deviation time segment group is normalized to obtain the duration index of the deviation time segment group, which reflects the degree of inconsistency in the duration between time segments.

[0096] Further, the sequence in which the deviation values on each temperature deviation segment in the deviation time segment group are distributed in chronological order is used as the time segment deviation sequence of each temperature deviation segment. The DTW matching algorithm is used for the time segment deviation sequences of two temperature deviation segments in the deviation time segment group to obtain the DTW value of the deviation time segment group. The DTW value represents the similarity between sequences. The smaller the DTW value, the higher the similarity between the two sequences after being aligned in time.

[0097] It should be noted that DTW is a dynamic programming algorithm used to compare two sequences that may not be aligned in time. The method of obtaining the DTW value through DTW matching is a well-known technical means for those skilled in the art and will not be elaborated here.

[0098] Therefore, the DTW value of the deviation time segment group is subjected to negative correlation mapping and normalization to obtain the trend weight of the deviation time segment group. For deviation temperature segments with the same change trend, their corresponding environmental heat dissipation effects are relatively close, so a higher trust weight is given. It should be noted that negative correlation mapping is a well-known technical means for those skilled in the art, such as in the form of inverse proportion or negative exponential power, etc., and will not be elaborated and restricted here.

[0099] Finally, the product of the trend weight and the duration index of the deviation time segment group is used as the time sequence deviation index of the deviation time segment group. Through trend analysis adjustment, the robustness of the duration analysis is improved. The larger the time sequence deviation index, the lower the similarity degree of the adjustment duration between temperature deviation segments.

[0100] S413: Combine the change deviation index and the time sequence deviation index of each deviation time segment group to obtain the environmental heat dissipation disorder degree of the time sequence current sequence.

[0101] Finally, by combining the difference analysis in two directions and through the inconsistency situation between two-by-two temperature deviation segments, the more serious the inconsistency situation on the time sequence current sequence, the more complex the situation of different environmental heat dissipations on the time sequence current sequence is reflected.

[0102] In an embodiment of the present invention, the product of the change deviation index and the timing deviation index of each deviation time period group is used as the difference index of each deviation time period group, reflecting the difference situation in each deviation time period group. The mean value of the difference indexes of all deviation time period groups is used as the environmental heat dissipation disorder degree of the timing current sequence. The greater the environmental heat dissipation disorder degree, the worse the stability of the environmental heat dissipation, and the higher the error reporting degree to be considered in subsequent monitoring.

[0103] Thus, the further analysis of the environmental heat dissipation stability is completed.

[0104] S5: Combine the electrical parameter environmental instability degree, the heat dissipation condition change degree, and the environmental heat dissipation disorder degree of the timing current to obtain the monitoring sensitivity; adjust the monitoring range of the power monitoring based on the monitoring sensitivity for monitoring.

[0105] When the current electrical parameter environment is relatively stable and the heat dissipation situation is also relatively stable, the attention to abnormal monitoring needs to be higher, and the monitoring is more sensitive to improve the abnormal monitoring accuracy. On the contrary, when the environmental stability is poor, the monitoring sensitivity needs to be reduced to reduce the possibility of abnormal monitoring error reporting.

[0106] Preferably, in an embodiment of the present invention, the method for obtaining the monitoring sensitivity includes:

[0107] First, perform weighted summation on the heat dissipation condition change degree and the environmental heat dissipation disorder degree of the timing current to obtain the heat dissipation environmental instability degree of the timing current, which reflects the instability degree of the heat dissipation situation in combination with the overall and local analysis of the environmental heat dissipation. In an embodiment of the present invention, the weight values of the weighted summation are all 0.5, and the specific weight values can be adjusted by the implementer himself / herself and are not limited here.

[0108] Finally, perform negative correlation mapping and normalization processing on the product of the heat dissipation environmental instability degree and the electrical parameter environmental instability degree of the timing current to obtain the monitoring sensitivity. Considering the stability of the electrical parameter environment and the heat dissipation environment, the higher the instability degree, the lower the required monitoring sensitivity.

[0109] Conventional online power monitoring methods for PTC heaters usually divide the current power into ranges. For example, if the current preset standard power is 100W, a change range of ±10% will be given, and if the change exceeds this range, the power is determined to be abnormal. However, considering the impact of complex situations on abnormal monitoring, in an embodiment of the present invention, the change range is adjusted based on the monitoring sensitivity to reduce the monitoring error.

[0110] In the embodiment of the present invention, the product of the monitoring sensitivity and the preset adjustment range is used as the adjustment range. The higher the sensitivity, the greater the adjustment degree. The difference between the preset maximum range and the adjustment range is used as the change range. By narrowing the change range, the monitoring accuracy in a stable environment is improved. If the power of the PTC heater in the time-sequence current series is outside the change range of the preset standard power, it indicates that the power exceeds the allowable range, and the monitoring result is abnormal.

[0111] In the embodiment of the present invention, the preset adjustment range is set to 10%, the maximum range is 15%, and the preset standard power is 100W. The specific values can be adjusted by the implementer according to the specific implementation situation and are not limited here. For example, when the obtained monitoring sensitivity is 0.7, the change range is ±[15% - (0.7×10%)], the adjustment range is 7%, and the change range is 8%. Given a relatively higher sensitivity, when the power exceeds the ±8% range of 100W, it indicates that there is a power abnormality, otherwise it is normal.

[0112] In summary, the present invention determines the instability degree of the electrical parameter environment of the PTC heater at its own heating gear through the unstable situation of the current current and the historical current approaching the Curie point temperature. By the characteristic that the PTC heater has a Curie temperature point and the current is limited when approaching the Curie temperature point, the performance of the electrical parameters during the heating process is expanded, and the accuracy of analyzing the electrical parameter environment is improved. The heat loss is reflected by the temperature deviation in the time sequence, and the possible influence of environmental heat dissipation is reflected according to the trend fluctuation of the deviation, so as to obtain the change degree of the heat dissipation condition. Considering the influence of the unstable heat dissipation environment on the actual adjustment judgment, it provides a data basis for subsequent environmental impact analysis. Under the influence of complex environmental factors, the instability of the environmental heat dissipation change makes the current change feedback with a delay effect higher. The time period with a higher feedback is determined by the deviation from the gear temperature, and the degree of environmental heat dissipation disorder is evaluated according to the difference between the deviation segments, reducing the error caused by complex environmental factors during subsequent monitoring. Finally, the monitoring sensitivity is comprehensively adjusted through the electrical parameter environment stability, the change degree of the heat dissipation condition, and the degree of environmental heat dissipation disorder, making the power monitoring range more reliable. The present invention adjusts the monitoring degree of the power quantization range of the PTC heater affected by the heat dissipation environment through analysis, improves the monitoring accuracy in different environments, and makes the monitoring result more reliable.

[0113] Embodiment 2:

[0114] The present invention also provides a power on-line monitoring system for a PTC heater, including:

[0115] A data acquisition module, configured to collect the time-sequence current series during the heating process, the output temperature and the ambient temperature of the PTC heater at each moment, and obtain the historical current series when heating to the current preset gear temperature;

[0116] An electrical parameter environment analysis module, configured to obtain the instability degree of the electrical parameter environment of the sequential current sequence according to the instability of the current deviation between the sequential current sequence and the historical current sequence at the temperature approaching the Curie point;

[0117] A heat dissipation condition change analysis module, configured to obtain the change degree of the heat dissipation condition of the sequential current sequence according to the trend fluctuation of the deviation change between the output temperature and the ambient temperature at the corresponding time sequence of the sequential current sequence;

[0118] An environmental heat dissipation disorder analysis module, configured to determine the temperature deviation section in the sequential current sequence through the deviation degree between the output temperature and the currently preset gear temperature at the corresponding time sequence of the sequential current sequence; analyze the differences in temperature deviation, current change, and time period continuous trend among different temperature deviation sections in the sequential current sequence, and obtain the environmental heat dissipation disorder degree of the sequential current sequence;

[0119] An adjustment monitoring module, configured to obtain the monitoring sensitivity by combining the instability degree of the electrical parameter environment, the change degree of the heat dissipation condition, and the environmental heat dissipation disorder degree of the sequential current; and monitor based on the monitoring sensitivity by adjusting the range of power monitoring.

[0120] It should be noted that the system provided in the above embodiment is only illustrated by the division of the above functional modules. In actual applications, the above functions can be allocated to different functional module units according to needs, that is, the internal structure of the system is divided into different functional module units to complete all or part of the functions described above. Since the specific implementation process of a power online monitoring system for a PTC heater in this embodiment is the same as the specific implementation process of a power online monitoring method for a PTC heater described above, it will not be elaborated here too much.

[0121] Embodiment 3:

[0122] The present invention also provides a power online monitoring device for a PTC heater, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of a power online monitoring method for a PTC heater as described in any one of the above are implemented.

[0123] It should be noted that the above sequence of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0124] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

Claims

1. A method for online power monitoring of a PTC heater, characterized in that: The method comprises: Collect the time-series current sequence during the heating process and the output temperature and ambient temperature of the PTC heater at each moment, and obtain the historical current sequence when heating to the current preset gear temperature; According to the instability of the current deviation between the time series current sequence and the historical current sequence approaching the Curie point temperature, the electrical parameter environmental instability of the time series current sequence is obtained; According to the trend fluctuation of the deviation change between the output temperature and the ambient temperature in the corresponding time sequence of the time sequence current sequence, the degree of change of the heat dissipation condition of the time sequence current sequence is obtained; Determine the temperature deviation segment in the time-series current sequence by the degree of deviation between the output temperature in the time sequence corresponding to the time sequence of the time sequence current sequence and the current preset gear temperature; Analyze the differences in temperature deviation, current change, time duration and deviation value distribution trend between different temperature deviation segments in the time sequence current sequence to obtain the environmental heat dissipation disorder of the time sequence current sequence; The monitoring sensitivity is obtained by combining the environmental instability of the electrical parameters of the time-series current sequence, the variation of the heat dissipation conditions and the environmental heat dissipation disorder; the power monitoring range is adjusted based on the monitoring sensitivity for monitoring; The method for obtaining the degree of change of the heat dissipation condition includes: The numerical difference between the output temperature and the ambient temperature at each moment corresponding to the time series current sequence is used as the heat loss value at each moment; the heat loss values ​​are arranged in time series to obtain a heat loss sequence; The principal component direction of the heat loss sequence is obtained through PCA principal component analysis; the angle between the principal component direction and the horizontal straight line is normalized as the degree of change of the heat dissipation condition of the time series current sequence.

2. The method for online power monitoring of a PTC heater according to claim 1, characterized in that: The method for obtaining the electrical parameter environment instability comprises: For any current sequence, the current curve of the current sequence is obtained by curve fitting; the slope of each moment in the current curve is obtained, and the moment corresponding to the maximum slope is taken as the moment of the change point; The numerical difference between the current data at each moment in the current sequence and the current data on the circuit curve is used as the fitting deviation value at each moment in the current sequence; Normalize the time interval between each moment and the change point moment to obtain the stable weight of each moment; After weighting all the fitting deviation values ​​with the stability weight at each moment as the weight, the standard deviation is calculated to obtain the instability factor of the current sequence; After calculating the difference in the instability factor between the time series current sequence and each historical current sequence, the mean of all the differences is calculated to obtain the electrical parameter environmental instability of the time series current sequence.

3. The method for online power monitoring of a PTC heater according to claim 1, characterized in that: The method for determining the temperature deviation section includes: Normalize the numerical difference between the output temperature at each moment in the time series current sequence and the current preset gear temperature to obtain the deviation value at each moment; take the moment when the deviation value is greater than the preset deviation threshold as the deviation temperature moment; The continuously distributed deviation temperature moments in the time series current sequence are merged to obtain the temperature deviation segment.

4. The method for online power monitoring of a PTC heater according to claim 3, characterized in that: The method for obtaining the environmental heat dissipation disorder degree includes: Every two different temperature deviation sections in the timing current sequence are regarded as a deviation period group; For any deviation period group, combining the difference between the maximum current changes and the difference between the maximum deviation values ​​between the temperature deviation segments in the deviation period group, a variation deviation index of the deviation period group is obtained; According to the time period continuous difference between the temperature deviation segments in the deviation time period group and the similarity of the deviation value distribution trend, the timing deviation index of the deviation time period group is obtained; The environmental heat dissipation disorder degree of the timing current sequence is obtained by combining the variation deviation index and the timing deviation index of each deviation period group.

5. The method for online power monitoring of a PTC heater according to claim 4, characterized in that: The method for obtaining the timing deviation indicator includes: Normalizing the difference between the lengths of two temperature deviation periods in the deviation period group to obtain a duration index of the deviation period group; The sequence of deviation values ​​distributed in time sequence on each temperature deviation segment in the deviation time segment group is used as the time segment deviation sequence of each temperature deviation segment; The DTW matching algorithm is used for the time period deviation sequence of the two temperature deviation segments in the deviation time period group to obtain the DTW value of the deviation time period group; the DTW value of the deviation time period group is negatively correlated and normalized to obtain the trend weight of the deviation time period group; The product of the trend weight and the duration index of the deviation period group is used as the timing deviation index of the deviation period group.

6. The method for online power monitoring of a PTC heater according to claim 1, characterized in that: The method for obtaining the monitoring sensitivity includes: The heat dissipation condition variation degree of the timing current sequence and the environmental heat dissipation disorder degree are weightedly summed to obtain the heat dissipation environment instability of the timing current sequence; The product of the heat dissipation environment instability of the timing current sequence and the electrical parameter environment instability is negatively correlated and normalized to obtain the monitoring sensitivity.

7. The method for online power monitoring of a PTC heater according to claim 1, characterized in that: The monitoring of the power monitoring range based on the monitoring sensitivity adjustment includes: The product of the monitoring sensitivity and the preset adjustment range is used as the adjustment range; the difference between the preset maximum range and the adjustment range is used as the variation range; If the power of the PTC heater in the timing current sequence is outside the variation range of the preset standard power, the monitoring result is abnormal.

8. A power online monitoring system for PTC heaters, characterized in that: include: The data acquisition module is used to collect the time-series current sequence during the heating process and the output temperature and ambient temperature of the PTC heater at each moment, and obtain the historical current sequence heated to the current preset gear temperature; An electrical parameter environment analysis module is used to obtain the electrical parameter environment instability of the time-series current sequence according to the instability of the current deviation between the time-series current sequence and the historical current sequence approaching the Curie point temperature; The heat dissipation condition change analysis module is used to obtain the degree of change of the heat dissipation condition of the time series current sequence according to the trend fluctuation of the deviation change between the output temperature and the ambient temperature in the time series corresponding to the time series current sequence; The environmental heat dissipation disorder analysis module is used to determine the temperature deviation segment in the time-series current sequence by the degree of deviation between the output temperature in the time sequence corresponding to the time sequence of the time sequence current sequence and the current preset gear temperature; analyze the differences between different temperature deviation segments in the time sequence current sequence in terms of temperature deviation, current change, time period duration and deviation value distribution trend, and obtain the environmental heat dissipation disorder of the time sequence current sequence; The adjustment monitoring module is used to obtain the monitoring sensitivity by combining the environmental instability of the electrical parameters of the timing current sequence, the variation of the heat dissipation conditions and the environmental heat dissipation disorder; The power monitoring range is adjusted based on the monitoring sensitivity to perform monitoring; The method for obtaining the degree of change of the heat dissipation condition includes: The numerical difference between the output temperature and the ambient temperature at each moment corresponding to the time series current sequence is used as the heat loss value at each moment; the heat loss values ​​are arranged in time series to obtain a heat loss sequence; The principal component direction of the heat loss sequence is obtained through PCA principal component analysis; the angle between the principal component direction and the horizontal straight line is normalized as the degree of change of the heat dissipation condition of the time series current sequence.

9. A power online monitoring device for a PTC heater, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for online power monitoring of a PTC heater as claimed in any one of claims 1 to 7 are implemented.

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