A method and system for diagnosing operating faults of a PTC heating device

Abstract

The present invention relates to the technical field of electronic digital data processing, and particularly relates to a method and system for diagnosing operation faults of a PTC heating device, including: determining the severity of the change in the branch current of the PTC aluminum tube under the surface temperature data according to the slope of the electrothermal sample points on the electrothermal change curve formed by the branch current data and the surface temperature data of the PTC aluminum tube, so as to determine the possibility of the thermal performance risk of the PTC heating device, combining the vehicle interior temperature data, the initial temperature of the air at the PTC air inlet and the air inlet rate to obtain the degree of PTC fault manifestation at the current moment, and then combining the energized current data input to the PTC main circuit to obtain the PTC operation warning index at the current moment for fault alarm. By combining the analysis of the resistance thermal sensitivity characteristics of the PTC electrothermal element and the air characteristics entering the PTC device in the actual scenario, the present invention improves the warning diagnosis accuracy of the operation faults of the automotive PTC.

Description

Technical Field

[0001] The invention relates to the technical field of electronic digital data processing, and in particular to an operation fault diagnosis method and system for a PTC heating device. Background Art

[0002] In the automotive field, PTC stands for positive temperature coefficient thermistor heating device, which is an automotive electric heat conversion heater, mainly used to preheat the engine in winter and provide a warm environment inside the car. With long-term use, the internal components of the device may age and fail, so fault warning diagnosis of PTC heating devices is of great safety significance.

[0003] The core component of the PTC heating device is a semiconductor element with internal electrothermal conversion. When current flows through the element, heat is generated, and then the heat sink diffuses the heat into the car through wind. The semiconductor element has good resistance thermal sensitivity. When the temperature rises, its resistance increases, thereby reducing the branch current to avoid excessive temperature.

[0004] Existing problems: Traditional methods often use threshold judgments on the temperature when the interior of the car tends to stabilize. If the preset temperature threshold is not reached, it means that the PTC may have an operational failure. In actual scenarios, the final temperature inside the car is not only related to the PTC heating capacity, but also to the initial temperature and wind speed of the air blown into the car, resulting in low warning accuracy based only on temperature threshold judgment. At the same time, the threshold judgment method does not combine the characteristics of the electrothermal conversion element for analysis, and fails to grasp the operating principles of the PTC core components, further reducing the accuracy of early warning diagnosis of operational failures. Summary of the invention

[0005] The invention provides an operation fault diagnosis method and system for a PTC heating device to solve the existing problems.

[0006] A method and system for diagnosing an operating fault of a PTC heating device of the present invention adopts the following technical solution:

[0007] An embodiment of the present invention provides a method for diagnosing an operation fault of a PTC heating device, the method comprising the following steps:

[0008] During the current period of operation of the automobile PTC heating device, the in-vehicle temperature data, the current data of the PTC total circuit input, the air intake rate and the initial temperature of the air at the PTC air inlet, and the branch current data and surface temperature data corresponding to each PTC aluminum tube are obtained at each moment;

[0009] According to the slope of the electric heating sample point on the electric heating change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times, determine the severity of the change of the branch current of each PTC aluminum tube under each surface temperature data;

[0010] Determine the thermal performance risk possibility of the PTC heating device according to the correlation between the surface temperature data corresponding to each PTC aluminum tube at all times and the severity of the change of the branch current of each PTC aluminum tube at each surface temperature data;

[0011] At the current moment, according to the difference between the surface temperature data corresponding to the PTC aluminum tube and the temperature data in the vehicle and the initial temperature of the wind at the PTC air inlet, combined with the air intake rate of the PTC air inlet and the thermal performance risk possibility of the PTC heating device, the PTC fault performance degree at the current moment is obtained;

[0012] According to the difference between the power-on current data of the PTC total circuit input at all times, combined with the degree of PTC fault manifestation at the current moment, the PTC operation warning index at the current moment is obtained; and a fault alarm is performed based on the size of the PTC operation warning index at the current moment.

[0013] Furthermore, the method of determining the severity of the branch current change of each PTC aluminum tube under each surface temperature data according to the slope of the electrothermal sample point on the electrothermal change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times includes the following specific steps:

[0014] A coordinate system is constructed with the surface temperature data as the horizontal axis and the branch current data as the vertical axis;

[0015] In the coordinate system, The coordinate position of the branch current data and surface temperature data of the PTC aluminum tube at each moment is taken as the The electric heating sample points of the PTC aluminum tube at each moment are The electric heating sample points of the PTC aluminum tube at all times are fitted using the least squares method to obtain the The electric heating curve of a PTC aluminum tube;

[0016] In the said On the electric heating change curve of the PTC aluminum tube, the maximum and minimum values ​​of the absolute values ​​of the slopes of all electric heating sample points are counted, and the difference between the maximum value and the minimum value is recorded as the range value. The difference between the absolute value of the slope of the first electric heating sample point and the minimum value is recorded as the first difference. The surface temperature data corresponding to the electric heating sample point is used as the reference temperature, and the ratio of the first difference value to the range value is recorded as the first The degree to which the branch current of a PTC aluminum tube changes at the reference temperature.

[0017] Furthermore, the determination of the thermal performance risk possibility of the PTC heating device includes the following specific steps:

[0018] For The surface temperature data of each PTC aluminum tube at all times are used in chronological order to form a surface temperature time series sequence. In the surface temperature time series sequence, the first The severity of the change of the branch current of each PTC aluminum tube under each surface temperature data constitutes an electrothermal severity time series, and the Pearson correlation coefficient between the surface temperature time series and the electrothermal severity time series is recorded as The resistance thermal sensitivity of a PTC aluminum tube during the current period of operation of the automobile PTC heating device;

[0019] Divide the first Several historical periods of the same conditions for a PTC aluminum tube;

[0020] According to the said A method for obtaining the resistance thermal sensitivity of a PTC aluminum tube in the current period of operation of the automobile PTC heating device, and obtaining the The resistance thermal sensitivity of a PTC aluminum tube in each historical period of the same conditions when the automobile PTC heating device is running;

[0021] According to the said The resistance thermal sensitivity of the PTC aluminum tube in each historical period of the same conditions when the automobile PTC heating device is running and the The difference between the resistance thermal sensitivity of the first PTC aluminum tube in the current period of operation of the automobile PTC heating device is determined The difference in thermal sensitivity history of each PTC aluminum tube;

[0022] Calculate the mean of the thermal sensitivity history differences of all PTC aluminum tubes as the second mean, calculate the absolute value of the difference between the thermal sensitivity history difference of each PTC aluminum tube and the second mean, take the sum of the absolute values ​​of the difference between the thermal sensitivity history differences of all PTC aluminum tubes and the second mean as the first sum, and take the product of the first sum and the second mean as the thermal performance risk possibility of the PTC heating device.

[0023] Further, the first The specific steps of the same historical period of a PTC aluminum tube are as follows:

[0024] During the current period of operation of the automobile PTC heating device, the first moment of the Surface temperature data of a PTC aluminum tube and the surface temperature data of the th PTC aluminum tube at the last moment ;

[0025] During the historical period when the preset automotive PTC heating device is operating, in chronological order, taking the moment when the surface temperature data of the th PTC aluminum tube first appears as o'clock as the first starting moment. After the first starting moment, taking the moment when the surface temperature data of the th PTC aluminum tube first appears as o'clock as the first ending moment, and taking the period between the first starting moment and the first ending moment as the first same-condition historical period. After the first ending moment, taking the moment when the surface temperature data of the th PTC aluminum tube first appears as o'clock as the second starting moment. After the second starting moment, taking the moment when the surface temperature data of the th PTC aluminum tube first appears as o'clock as the second ending moment, and taking the period between the second starting moment and the second ending moment as the second same-condition historical period, and so on, to obtain several same-condition historical periods of the th PTC aluminum tube.

[0026] Furthermore, the specific steps for determining the thermal sensitivity historical difference degree of the th PTC aluminum tube are as follows:

[0027] Calculate the mean value of the resistance thermal sensitivity of the th PTC aluminum tube in all same-condition historical periods during the operation of the automotive PTC heating device, denoted as the first mean value. Take the normalized value of the absolute value of the difference between the resistance thermal sensitivity of the th PTC aluminum tube in the current period during the operation of the automotive PTC heating device and the first mean value as the thermal sensitivity historical difference degree of the th PTC aluminum tube.

[0028] Furthermore, the specific steps for obtaining the degree of PTC fault manifestation at the current moment are as follows:

[0029] At the current moment, based on the differences between the surface temperature data corresponding to the PTC aluminum tube and the in-vehicle temperature data and the initial temperature of the air at the PTC air inlet, determine the heat exchange efficiency at the current moment and the temperature difference between the initial temperature of the air and the temperature of the aluminum tube at the current moment;

[0030] The product of the temperature difference between the initial downwind temperature and the aluminum tube temperature at the current moment and the air inlet velocity of the PTC air inlet at the current moment is recorded as the wind speed influence degree at the current moment;

[0031] The ratio of the heat exchange efficiency at the current moment to the wind speed influence degree at the current moment is recorded as the modified thermal efficiency reflection coefficient at the current moment;

[0032] The ratio of the thermal performance risk possibility of the PTC heating device to the corrected thermal efficiency reflection coefficient at the current moment is used as the PTC fault manifestation degree at the current moment.

[0033] Furthermore, the determination of the heat exchange efficiency at the current moment and the temperature difference between the initial downwind temperature and the aluminum tube temperature at the current moment includes the following specific steps:

[0034] At the current moment, the mean of the surface temperature data corresponding to all PTC aluminum tubes is calculated, and the absolute value of the difference between the in-car temperature data and the mean of the surface temperature data corresponding to all the PTC aluminum tubes is used as the temperature difference between the in-car temperature and the aluminum tube temperature at the current moment. The inversely proportional normalized value of the temperature difference between the in-car temperature and the aluminum tube temperature at the current moment is used as the heat exchange efficiency at the current moment. The absolute value of the difference between the initial temperature of the wind at the PTC air inlet and the mean of the surface temperature data corresponding to all the PTC aluminum tubes is used as the temperature difference between the initial wind temperature and the aluminum tube temperature at the current moment.

[0035] Furthermore, the obtaining of the PTC operation warning indicator at the current moment includes the following specific steps:

[0036] Calculate the mean of the power-on current data of the PTC total circuit input at all times as the third mean, calculate the absolute value of the difference between the power-on current data of the PTC total circuit input at each moment and the third mean, and record the inversely proportional normalized value of the sum of the absolute values ​​of the difference between the power-on current data of the PTC total circuit input at all moments and the third mean as the target difference, and record the normalized value of the product of the target difference and the PTC fault manifestation degree at the current moment as the PTC operation warning index at the current moment.

[0037] Furthermore, the fault alarm is performed based on the size of the PTC operation warning indicator at the current moment, and the specific steps include the following:

[0038] If the PTC operation warning index at the current moment is greater than or equal to the preset first alarm threshold, a fault alarm is issued.

[0039] The present invention also proposes an operation fault diagnosis system for a PTC heating device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program stored in the memory to implement the steps of the aforementioned operation fault diagnosis method for a PTC heating device.

[0040] The beneficial effects of the technical solution of the present invention are:

[0041] In the embodiment of the present invention, the severity of the change of the current of the PTC aluminum tube branch containing the electric heating element with temperature is first evaluated, and the thermal performance risk possibility of the PTC device is obtained by combining the resistance thermal sensitivity characteristics of the electric heating element at different temperatures and the difference with historical data, so as to ensure the accuracy of the acquisition of the PTC operation warning index. Then, the degree of PTC fault manifestation is obtained by combining the intake characteristics entering the PTC device and the temperature difference characteristics between the aluminum tube and the temperature inside the vehicle, and the final warning index is obtained according to the stability of the PTC input current. At this point, the present invention can combine the resistance thermal sensitivity characteristics of the PTC electric heating element in the actual scene and the characteristics of the air entering the PTC device for combined analysis, thereby improving the accuracy of the early warning diagnosis of the automobile PTC operation fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A flowchart of a method for diagnosing an operating fault of a PTC heating device according to the present invention;

[0044] Figure 2 This is a schematic diagram of a PTC heating device for an automobile;

[0045] Figure 3 It is a schematic diagram of PTC electric heating element and heat dissipation fins;

[0046] Figure 4 This is a schematic diagram of the electric heating change curve of a PTC aluminum tube;

[0047] Figure 5 This is a schematic diagram of the electrothermal variation curve of a PTC aluminum tube in the current period and the historical period under the same conditions. DETAILED DESCRIPTION

[0048] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the operation fault diagnosis method and system of a PTC heating device proposed by the present invention, its specific implementation method, structure, characteristics and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0049] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0050] The following is a detailed description of a method and system for diagnosing operating faults of a PTC heating device provided by the present invention in conjunction with the accompanying drawings.

[0051] See also Figure 1 , which shows a flow chart of a method for diagnosing an operating fault of a PTC heating device provided by an embodiment of the present invention, the method comprising the following steps:

[0052] Step S001: During the current period of operation of the automobile PTC heating device, the in-vehicle temperature data, the current data of the PTC total circuit input, the air intake rate and the initial temperature of the wind at the PTC air inlet, and the branch current data and surface temperature data corresponding to each PTC aluminum tube are obtained at each moment.

[0053] During the current period of operation of the automobile PTC heating device, the in-vehicle temperature data at each moment, the power-on current data of the PTC total circuit input, the air intake rate and the initial temperature of the wind at the PTC air inlet, and the branch current data corresponding to each PTC aluminum tube and the surface temperature data of each PTC aluminum tube are collected.

[0054] It should be noted that: in this embodiment, a temperature sensor is used to collect various temperature data, an anemometer is used to collect the air intake speed, and a current transformer is used to collect various current data. The data collection frequency is once per second. This example is used for description. PTC heating devices are commonly used in the automotive field to provide a warm and comfortable environment in the car. Figure 2 The PTC heating device mainly relies on the internal PTC electric heating element and heat sink fins. The schematic diagram of the PTC electric heating element and heat sink fins is shown in Figure 3As shown, there are multiple aluminum tubes in the automobile PTC heating device, and each aluminum tube is wrapped with multiple PTC electric heating elements. In actual situations, different numbers of aluminum tubes are selected to be energized according to different temperature heating requirements. When current flows through the PTC electric heating element, heat is emitted and diffused into the car through the heat sink, thereby increasing the temperature inside the car.

[0055] Step S002: Determine the severity of the branch current change of each PTC aluminum tube at each surface temperature data according to the slope of the electrothermal sample point on the electrothermal change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times.

[0056] It should be noted that: in this embodiment, a more accurate PTC heating device operation fault warning result is obtained by combining and analyzing the resistance thermal sensitivity characteristics of the PTC electric heating element and the air intake conditions of the PTC device in the actual scene. Because the resistance value of the PTC electric heating element increases with the increase of temperature, the correlation of the temperature resistance change of a single aluminum tube is first analyzed, and the thermal sensitivity of a single aluminum tube is obtained according to the temperature stage of the aluminum tube in real time, and then the thermal performance risk possibility of a single aluminum tube is obtained by combining the historical data performance and the differences between different aluminum tubes. At the same time, the degree of PTC fault performance is obtained by combining the PTC air intake conditions, so as to obtain the PTC operation warning index.

[0057] When evaluating the degree to which the aluminum tube branch current in the PTC device changes with temperature at various temperatures, it is necessary to consider that the PTC aluminum tube is composed of various PTC heating elements in parallel, and the resistance of the heating element increases with increasing temperature, and the higher the temperature, the more drastic the resistance change. Therefore, the PTC aluminum tube also has a sensitive change relationship between resistance and temperature. Because the aluminum tube branch current can reflect the aluminum tube branch resistance, it is necessary to first evaluate the degree to which the automobile PTC aluminum tube branch current changes with temperature during the current period.

[0058] Preferably, in one embodiment of the present invention, a method for obtaining the severity of the change of the branch current of each PTC aluminum tube under each surface temperature data includes:

[0059] First Taking a PTC aluminum tube as an example, during the current period of operation of the automobile PTC heating device, a coordinate system is constructed with the surface temperature data as the horizontal axis and the branch current data as the vertical axis. The coordinate position of the branch current data and surface temperature data of the PTC aluminum tube at each moment is taken as the The electric heating sample points of the PTC aluminum tube at each moment are The electric heating sample points of the PTC aluminum tube at all times are fitted using the least squares method to obtain the The electric heating change curve of a PTC aluminum tube.

[0060] What needs to be explained is: a schematic diagram of the electric heating change curve of a PTC aluminum tube, such as Figure 4 As shown, Figure 4 The horizontal axis is temperature in degrees Celsius ( ), the vertical axis is the aluminum tube branch current, the unit is ampere (A). The least square method is a well-known technology, and the specific method will not be introduced here.

[0061] Get the The slope of each electric heating sample point on the electric heating change curve of a PTC aluminum tube is a well-known operation. For a single electric heating sample point on the electric heating change curve corresponding to the PTC aluminum tube, if the absolute value of its slope is larger, it means that at the temperature corresponding to the electric heating sample point, the resistance of the aluminum tube changes more dramatically with temperature, and the branch current changes more dramatically.

[0062] In the On the electric heating change curve of a PTC aluminum tube, the maximum value of the absolute value of the slope of all electric heating sample points is counted With minimum , the maximum value Subtract the minimum value The difference between The absolute value of the slope of the electric heating sample points minus the minimum value The difference is recorded as the first difference, and the The surface temperature data corresponding to the electric heating sample point is used as the reference temperature, and the ratio of the first difference value to the range value is recorded as the first The degree of change of branch current of a PTC aluminum tube at the reference temperature.

[0063] According to the above method, the severity of the change of the branch current of each PTC aluminum tube under various surface temperature data can be obtained.

[0064] Step S003: Determine the thermal performance risk possibility of the PTC heating device according to the correlation between the surface temperature data corresponding to each PTC aluminum tube at all times and the severity of the change of the branch current of each PTC aluminum tube under each surface temperature data.

[0065] What needs to be explained is that: based on the severity of the branch current change, the possibility of thermal performance risk is obtained according to the real-time temperature stage of the aluminum tube and the characteristics of historical data, and then the degree of PTC fault performance is obtained in combination with the air intake situation of the device. Because the higher the temperature stage of the aluminum tube, the more drastic the change of the aluminum tube resistance, the severity of the change of the aluminum tube branch current is corrected according to the temperature stage, and the thermal sensitivity of the resistance of a single aluminum tube is obtained, and then the possibility of thermal performance risk is obtained through the difference in the thermal sensitivity of the resistance in the real-time and historical data at the same temperature and the difference between different aluminum tubes. At the same time, the worse the air intake effect of the PTC air inlet, the worse the effect of transferring the heat generated by the aluminum tube to the car, so the degree of PTC fault performance is obtained in combination with the air intake situation.

[0066] Preferably, in one embodiment of the present invention, the method for obtaining the thermal performance risk possibility of the PTC heating device includes:

[0067] Still For example, during the current period of operation of the automobile PTC heating device, for the The surface temperature time series of each PTC aluminum tube is formed by using the surface temperature data at all times in chronological order. In the surface temperature time series, the first The severity of the change of the branch current of each PTC aluminum tube under each surface temperature data constitutes the time series of the electric heating severity. The Pearson correlation coefficient between the surface temperature time series and the electric heating severity time series is recorded as The resistance thermal sensitivity of a PTC aluminum tube during the current period of operation of the automobile PTC heating device.

[0068] It should be noted that the Pearson correlation coefficient is a well-known technology, and the specific method is not introduced here. The larger the Pearson correlation coefficient, the more positively correlated the two time series are. Since the resistance of the electric heating element in the aluminum tube increases with the temperature, and the higher the temperature value, the more drastic the increase, the surface temperature of the aluminum tube should be positively correlated with the intensity of the electric heating change.

[0069] The preset historical time period of operation of the automobile PTC heating device is all time periods of operation of the automobile PTC heating device within three months before the current time period of operation of the automobile PTC heating device, and this is used as an example for description.

[0070] During the historical period of operation of the preset automobile PTC heating device, the branch current data and surface temperature data corresponding to each PTC aluminum tube at each moment are collected.

[0071] During the current period of operation of the automobile PTC heating device, the first moment of the Surface temperature data of PTC aluminum tube And the last moment Surface temperature data of PTC aluminum tube .

[0072] In the preset historical period of operation of the automobile PTC heating device, in chronological order, the first occurrence of The surface temperature data of a PTC aluminum tube is The time at which the first starting time appears is taken as the first starting time. The surface temperature data of a PTC aluminum tube is The time at which the first condition occurs is taken as the first end time, the period from the first start time to the first end time is taken as the first historical period with the same condition, and after the first end time, the first occurrence of the The surface temperature data of a PTC aluminum tube is The time at which the first occurrence of The surface temperature data of a PTC aluminum tube is The moment of , as the second end time, the period between the second start time and the second end time as the second historical period with the same conditions, and so on, to obtain the first Several historical periods of the same conditions for a PTC aluminum tube.

[0073] It should be noted that the preset historical period of operation of the automobile PTC heating device is composed of multiple periods of operation of the automobile PTC heating device within three months. In the three historical months, the operation and shutdown states of the automobile PTC heating device are constantly changing. If the start time and the end time of a certain historical period with the same conditions are respectively in different periods of operation of the automobile PTC heating device, then this embodiment does not analyze this historical period with the same conditions. A schematic diagram of the electric heating change curve of a PTC aluminum tube in the current period and the historical period with the same conditions, as shown in Figure 5 As shown, Figure 5 The horizontal axis is temperature in degrees Celsius ( ), the vertical axis is the aluminum tube branch current, the solid line is the real-time data, that is, the electric heating change curve in the current period, and the dotted line is the historical data, that is, the electric heating change curve in multiple historical periods with the same conditions from the same temperature starting point to the same temperature end point in the current period.

[0074] According to A method for obtaining the resistance thermal sensitivity of a PTC aluminum tube in the current period of operation of the automobile PTC heating device, and obtaining the The resistance thermal sensitivity of a PTC aluminum tube in each historical period of the same conditions when the automobile PTC heating device is running.

[0075] Calculate the The average value of the thermal sensitivity of the resistance of the PTC aluminum tube in all historical periods of the same conditions when the automobile PTC heating device is running is recorded as the first average value. The normalized value of the absolute value of the difference between the resistance thermal sensitivity of the first PTC aluminum tube in the current period of operation of the automobile PTC heating device and the first mean value is used as the first The thermal sensitivity of each PTC aluminum tube is different.

[0076] It should be noted that the normalized value of the absolute value of the above difference is used in this embodiment. Linear normalization function, normalizes the absolute value of the difference to In the range, take this as an example. The greater the difference between the thermal sensitivity of the resistance of the aluminum tube in the real-time period and the average thermal sensitivity of the resistance of the historical period, the greater the difference between the thermal sensitivity of the resistance of the aluminum tube in the real-time period and the average thermal sensitivity of the resistance of the historical period. There may be a real-time failure problem with an aluminum tube.

[0077] Calculate the mean of the thermal sensitivity history differences of all PTC aluminum tubes as the second mean, calculate the absolute value of the difference between the thermal sensitivity history difference of each PTC aluminum tube and the second mean, and take the sum of the absolute values ​​of the differences between the thermal sensitivity history differences of all PTC aluminum tubes and the second mean as the first sum, and take the product of the first sum and the second mean as the thermal performance risk possibility of the PTC heating device.

[0078] It should be noted that the number of electric heating elements inside each PTC aluminum tube is the same. Therefore, the greater the difference between each aluminum tube and the mean level of the thermal sensitivity historical difference of all aluminum tubes, and the mean level of the thermal sensitivity historical difference of all aluminum tubes is itself large, the greater the possibility that the aluminum tube is in an abnormal thermal performance state at this time.

[0079] Step S004: At the current moment, based on the differences between the surface temperature data corresponding to the PTC aluminum tube and the temperature data inside the vehicle and the initial temperature of the wind at the PTC air inlet, combined with the air intake rate of the PTC air inlet and the thermal performance risk possibility of the PTC heating device, the degree of PTC fault manifestation at the current moment is obtained.

[0080] It should be noted that the heat generated by the electric heating element in the PTC aluminum tube often needs to be diffused into the air entering the PTC device through the heat dissipation fins, and then the hot air is output to the vehicle. When the PTC device has an abnormal operation failure, it may cause the heat generated by the electric heating element to be difficult to transmit to the vehicle, resulting in poor heat exchange efficiency. Therefore, the thermal efficiency reflection coefficient of the PTC can be obtained based on the heat exchange performance.

[0081] Preferably, in one embodiment of the present invention, the method for obtaining the PTC fault manifestation degree at the current moment includes:

[0082] In this embodiment, the last moment in the current period of operation of the automobile PTC heating device is the current moment.

[0083] At the current moment, calculate the mean of the surface temperature data corresponding to all PTC aluminum tubes, and take the absolute value of the difference between the in-car temperature data and the mean of the surface temperature data corresponding to all PTC aluminum tubes as the temperature difference between the in-car temperature and the aluminum tube temperature at the current moment. , the inversely proportional normalized value of the temperature difference between the temperature inside the vehicle and the temperature of the aluminum tube at the current moment is taken as the heat exchange efficiency at the current moment.

[0084] It should be noted that: in this embodiment, To present The inverse proportional relationship and normalization processing of the implementation can be set according to the actual situation. It is an exponential function with a natural constant as the base. Since the greater the temperature difference, the worse the heat exchange efficiency between the temperature inside the car and the temperature of the aluminum tube, the inverse proportional normalized value of the temperature difference is used as the heat exchange efficiency.

[0085] At the current moment, calculate the mean of the surface temperature data corresponding to all PTC aluminum tubes, and take the absolute value of the difference between the initial temperature of the wind at the PTC air inlet and the mean of the surface temperature data corresponding to all PTC aluminum tubes as the temperature difference between the initial wind temperature and the aluminum tube temperature at the current moment. .

[0086] Will The product of the wind speed at the PTC air inlet at the current moment is recorded as the wind speed influence degree at the current moment.

[0087] It should be noted that: when the air intake rate of the PTC air inlet is faster, the faster flowing air can quickly carry heat into the car, increasing the heat exchange efficiency. At the same time, the greater the temperature difference between the initial wind temperature and the temperature of the aluminum tube, the temperature diffusion rate can be further increased, which further illustrates that the air intake condition at this time is more conducive to the diffusion and propagation of heat.

[0088] The ratio of the heat exchange efficiency at the current moment to the degree of influence of the wind speed at the current moment is recorded as the corrected thermal efficiency reflection coefficient at the current moment.

[0089] The ratio of the thermal performance risk possibility of the PTC heating device to the corrected thermal efficiency reflection coefficient at the current moment is taken as the PTC fault manifestation degree at the current moment.

[0090] It should be noted that since the heat exchange efficiency is affected by both the operating state of the PTC itself and the air intake conditions, in order to reduce the probability of a better air intake condition covering up a worse abnormal operating state, this embodiment corrects the heat exchange efficiency by the degree of wind speed influence, that is, the greater the degree of wind speed influence, the smaller the adjustment coefficient of the heat exchange efficiency. If the thermal performance risk of the PTC heating device is greater and the corrected thermal efficiency reflection coefficient is smaller, it means that the possibility of abnormal operation failure of the PTC is greater.

[0091] Step S005: According to the difference between the current data of the PTC total circuit input at all times, combined with the PTC fault performance level at the current moment, obtain the PTC operation warning index at the current moment; and perform a fault alarm based on the size of the PTC operation warning index at the current moment.

[0092] It should be noted that: since the stability of the PTC circuit's current will be affected under different power consumption conditions of the car, for example, when other items of the car consume a lot of power, the current of the PTC circuit may be unstable, and the confidence level of the fault performance of the PTC device will be reduced. Therefore, the real-time operation warning indicator of the PTC is obtained by combining the stability of the current and the degree of PTC fault performance.

[0093] Preferably, in one embodiment of the present invention, the method for obtaining the PTC operation warning indicator at the current moment includes:

[0094] In the current period when the automobile PTC heating device is running, the mean value of the current data of the PTC total circuit input at all times is calculated as the third mean value, the absolute value of the difference between the current data of the PTC total circuit input at each time and the third mean value is calculated, and the sum of the absolute values ​​of the difference between the current data of the PTC total circuit input at all times and the third mean value is calculated. The inverse proportional normalized value of is recorded as the target difference, and the normalized value of the product of the target difference and the PTC fault performance degree at the current moment is recorded as the PTC operation warning index at the current moment.

[0095] It should be noted that: in this embodiment, the normalized value of the above product is used in this embodiment Linear normalization function, normalizes the product to In the range, take this as an example to describe To present The inverse proportional relationship and normalization processing of the implementation can be set according to the actual situation. is an exponential function with a natural constant as its base. The larger the value is, the more unstable the current is, and the smaller the confidence level should be set for the current PTC fault performance.

[0096] The first alarm threshold is preset to 0.88, the second alarm threshold is preset to 0.68, and the fault observation time is preset to 8 seconds. This is taken as an example for description.

[0097] If the PTC operation warning index at the current moment is greater than or equal to the preset first alarm threshold, a fault alarm is issued.

[0098] It should be noted that after the fault alarm, the vehicle needs to be stopped for inspection in a safe manner. If the PTC operation warning index at the current moment is less than or equal to the preset second alarm threshold, it is considered that there is no fault. If the PTC operation warning index at the current moment is less than the preset first alarm threshold and greater than the preset second alarm threshold, it enters the operation fault waiting observation stage. If it is in the operation fault waiting observation stage for 8 consecutive seconds, a fault alarm will be issued and the vehicle will be stopped for inspection under the premise of safety.

[0099] The present invention also provides an operation fault diagnosis system for a PTC heating device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program stored in the memory to implement the steps of the aforementioned operation fault diagnosis method for a PTC heating device.

[0100] So far, the present invention is completed.

[0101] In summary, in the embodiment of the present invention, according to the slope of the electric heating sample point on the electric heating change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times, the severity of the branch current change of each PTC aluminum tube under each surface temperature data is determined, thereby determining the thermal performance risk possibility of the PTC heating device, combining the in-vehicle temperature data with the initial temperature of the wind at the PTC air inlet and the air intake rate, obtaining the degree of PTC fault performance at the current moment, and then combining the power-on current data input by the PTC total circuit to obtain the PTC operation warning index at the current moment for fault alarm. The present invention improves the early warning diagnosis accuracy of automobile PTC operation faults through the combined analysis of the resistance thermal sensitivity characteristics of the PTC electric heating element in actual scenarios and the characteristics of the air entering the PTC device.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for diagnosing an operating fault of a PTC heating device, characterized in that: The method comprises the following steps: During the current period of operation of the automobile PTC heating device, the in-vehicle temperature data, the current data of the PTC total circuit input, the air intake rate and the initial temperature of the air at the PTC air inlet, and the branch current data and surface temperature data corresponding to each PTC aluminum tube are obtained at each moment; According to the slope of the electric heating sample point on the electric heating change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times, determine the severity of the change of the branch current of each PTC aluminum tube under each surface temperature data; Determine the thermal performance risk possibility of the PTC heating device according to the correlation between the surface temperature data corresponding to each PTC aluminum tube at all times and the severity of the change of the branch current of each PTC aluminum tube at each surface temperature data; At the current moment, according to the difference between the surface temperature data corresponding to the PTC aluminum tube and the temperature data in the vehicle and the initial temperature of the wind at the PTC air inlet, combined with the air intake rate of the PTC air inlet and the thermal performance risk possibility of the PTC heating device, the PTC fault performance degree at the current moment is obtained; According to the difference between the power-on current data of the PTC total circuit input at all times, combined with the degree of PTC fault manifestation at the current moment, the PTC operation warning index at the current moment is obtained; and a fault alarm is performed based on the size of the PTC operation warning index at the current moment.

2. The method for diagnosing an operating fault of a PTC heating device according to claim 1, characterized in that: The method of determining the severity of the branch current change of each PTC aluminum tube under each surface temperature data according to the slope of the electrothermal sample point on the electrothermal change curve composed of the branch current data and the surface temperature data corresponding to each PTC aluminum tube at all times includes the following specific steps: A coordinate system is constructed with the surface temperature data as the horizontal axis and the branch current data as the vertical axis; In the coordinate system, The coordinate position of the branch current data and surface temperature data of the PTC aluminum tube at each moment is taken as the The electric heating sample points of the PTC aluminum tube at each moment are The electric heating sample points of the PTC aluminum tube at all times are fitted using the least squares method to obtain the The electric heating curve of a PTC aluminum tube; In the said On the electric heating change curve of the PTC aluminum tube, the maximum and minimum values ​​of the absolute values ​​of the slopes of all electric heating sample points are counted, and the difference between the maximum value and the minimum value is recorded as the range value. The difference between the absolute value of the slope of the first electric heating sample point and the minimum value is recorded as the first difference. The surface temperature data corresponding to the electric heating sample point is used as the reference temperature, and the ratio of the first difference value to the range value is recorded as the first The degree to which the branch current of a PTC aluminum tube changes at the reference temperature.

3. The method for diagnosing an operating fault of a PTC heating device according to claim 1, characterized in that: The specific steps of determining the thermal performance risk possibility of the PTC heating device are as follows: For The surface temperature data of each PTC aluminum tube at all times are used in chronological order to form a surface temperature time series sequence. In the surface temperature time series sequence, the first The severity of the change of the branch current of each PTC aluminum tube under each surface temperature data constitutes an electrothermal severity time series, and the Pearson correlation coefficient between the surface temperature time series and the electrothermal severity time series is recorded as The resistance thermal sensitivity of a PTC aluminum tube during the current period of operation of the automobile PTC heating device; Divide the first Several historical periods of the same conditions for a PTC aluminum tube; According to the said A method for obtaining the resistance thermal sensitivity of a PTC aluminum tube in the current period of operation of the automobile PTC heating device, and obtaining the The resistance thermal sensitivity of a PTC aluminum tube in each historical period of the same conditions when the automobile PTC heating device is running; According to the said The resistance thermal sensitivity of the PTC aluminum tube in each historical period of the same conditions when the automobile PTC heating device is running and the The difference between the resistance thermal sensitivity of the first PTC aluminum tube in the current period of operation of the automobile PTC heating device is determined The difference in thermal sensitivity history of each PTC aluminum tube; Calculate the mean of the thermal sensitivity history differences of all PTC aluminum tubes as the second mean, calculate the absolute value of the difference between the thermal sensitivity history difference of each PTC aluminum tube and the second mean, take the sum of the absolute values ​​of the difference between the thermal sensitivity history differences of all PTC aluminum tubes and the second mean as the first sum, and take the product of the first sum and the second mean as the thermal performance risk possibility of the PTC heating device.

4. The method for diagnosing an operation fault of a PTC heating device according to claim 3, characterized in that: The first The specific steps of the same historical period of a PTC aluminum tube are as follows: During the current period of operation of the automobile PTC heating device, the first moment of the Surface temperature data of PTC aluminum tube And the last moment Surface temperature data of PTC aluminum tube ; In the preset historical period of operation of the automobile PTC heating device, in chronological order, the first occurrence of The surface temperature data of a PTC aluminum tube is The time at which the first starting time appears is the first time after the first starting time. The surface temperature data of a PTC aluminum tube is The first time when the first condition occurs is taken as the first end time, the period from the first start time to the first end time is taken as the first same condition historical period, and the first occurrence of the first condition historical period after the first end time is taken as the first same condition historical period. The surface temperature data of a PTC aluminum tube is The time at which the first occurrence of The surface temperature data of a PTC aluminum tube is The time at which the second starting time is taken as the second end time, and the period from the second starting time to the second end time is taken as the second historical period with the same condition, and so on. Several historical periods of the same conditions for a PTC aluminum tube.

5. The method for diagnosing an operation fault of a PTC heating device according to claim 3, characterized in that: The determination The thermal sensitivity history difference of each PTC aluminum tube includes the following specific steps: Calculate the The average value of the thermal sensitivity of the resistance of the PTC aluminum tube in all historical periods of the same conditions when the automobile PTC heating device is running is recorded as the first average value. The normalized value of the absolute value of the difference between the resistance thermal sensitivity of the first PTC aluminum tube in the current period of operation of the automobile PTC heating device and the first mean value is used as the first The thermal sensitivity of each PTC aluminum tube is different.

6. The method for diagnosing operating faults of a PTC heating device according to claim 1, characterized in that: The specific steps of obtaining the current PTC fault manifestation degree are as follows: At the current moment, the heat exchange efficiency at the current moment and the temperature difference between the initial wind temperature and the aluminum tube temperature at the current moment are determined according to the difference between the surface temperature data corresponding to the PTC aluminum tube and the temperature data in the vehicle and the initial temperature of the wind at the PTC air inlet; The product of the temperature difference between the initial downwind temperature and the aluminum tube temperature at the current moment and the air inlet velocity of the PTC air inlet at the current moment is recorded as the wind speed influence degree at the current moment; The ratio of the heat exchange efficiency at the current moment to the wind speed influence degree at the current moment is recorded as the modified thermal efficiency reflection coefficient at the current moment; The ratio of the thermal performance risk possibility of the PTC heating device to the corrected thermal efficiency reflection coefficient at the current moment is used as the PTC fault manifestation degree at the current moment.

7. The method for diagnosing an operating fault of a PTC heating device according to claim 6, characterized in that: The specific steps of determining the heat exchange efficiency at the current moment and the temperature difference between the initial wind temperature and the aluminum tube temperature at the current moment are as follows: At the current moment, the mean of the surface temperature data corresponding to all PTC aluminum tubes is calculated, and the absolute value of the difference between the in-car temperature data and the mean of the surface temperature data corresponding to all the PTC aluminum tubes is used as the temperature difference between the in-car temperature and the aluminum tube temperature at the current moment. The inversely proportional normalized value of the temperature difference between the in-car temperature and the aluminum tube temperature at the current moment is used as the heat exchange efficiency at the current moment. The absolute value of the difference between the initial temperature of the wind at the PTC air inlet and the mean of the surface temperature data corresponding to all the PTC aluminum tubes is used as the temperature difference between the initial wind temperature and the aluminum tube temperature at the current moment.

8. The method for diagnosing operating faults of a PTC heating device according to claim 1, characterized in that: The specific steps of obtaining the PTC operation warning indicator at the current moment are as follows: Calculate the mean of the power-on current data of the PTC total circuit input at all times as the third mean, calculate the absolute value of the difference between the power-on current data of the PTC total circuit input at each moment and the third mean, and record the inversely proportional normalized value of the sum of the absolute values ​​of the difference between the power-on current data of the PTC total circuit input at all moments and the third mean as the target difference, and record the normalized value of the product of the target difference and the PTC fault manifestation degree at the current moment as the PTC operation warning index at the current moment.

9. The method for diagnosing operating faults of a PTC heating device according to claim 1, characterized in that: The specific steps of performing a fault alarm based on the size of the PTC operation warning indicator at the current moment are as follows: If the PTC operation warning index at the current moment is greater than or equal to the preset first alarm threshold, a fault alarm is issued.

10. An operation fault diagnosis system for a PTC heating device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is executed by a processor, the steps of the method for diagnosing operating faults of a PTC heating device as described in any one of claims 1 to 9 are implemented.

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