Full-automatic vacuum continuous drying equipment and drying method for electric appliance coil

Abstract

The invention relates to the technical field of drying, in particular to a full-automatic vacuum continuous drying device and method for an electric appliance coil, and the device comprises a data sensing unit which is used for applying basic heating current and periodic detection current to the electric appliance coil, and synchronously collecting the heating power data of the electric appliance coil and the air pressure data of a vacuum cavity; and the heating power fluctuation quantity and the cavity air pressure response quantity are extracted. And the flow resistance characteristic resolving unit is used for determining a flow resistance characteristic index according to the heating power fluctuation quantity and the cavity air pressure response quantity. And the state evaluation unit is used for determining the flow resistance characteristic change rate according to the flow resistance characteristic index. The closed-loop feedback unit is used for controlling the basic heating current to increase progressively under the condition that the flow resistance characteristic change rate is smaller than or equal to a preset threshold value; and under the condition that the flow resistance characteristic change rate is larger than a preset threshold value, the basic heating current is controlled to decrease progressively. The invention provides the vacuum drying equipment which can give consideration to both the drying efficiency and the product quality.

Description

Technical Field

[0001] This invention relates to the field of drying technology, specifically to a fully automatic vacuum continuous drying equipment and method for electrical coils. Background Technology

[0002] In the field of new energy vehicle manufacturing, the drive motor is a core power component. As a key component of the drive motor, the stator's winding insulation treatment process directly determines the motor's operational stability and service life. Vacuum continuous drying is a core process in the stator winding insulation treatment. By using a vacuum environment in conjunction with heating the coil, moisture inside the insulation material can be removed, ensuring the performance of the insulation layer. Therefore, developing efficient and stable fully automatic vacuum continuous drying technology for electrical coils has become an important research direction in the field of new energy vehicle motor manufacturing.

[0003] Currently, vacuum drying of electrical coils typically involves applying a heating current to the coil in conjunction with the vacuum environment of a vacuum chamber. During the process, physical quantities such as the macroscopic vacuum level of the chamber or the average temperature of the coil surface are monitored to adjust the heating current output, resulting in a relatively fixed control mode for the overall drying process. However, with increasingly compact motor structures and the dense, deep porous dielectric structure of the coil insulation layer, the channels for moisture vaporization and subsequent exhaust are narrow. This traditional vacuum drying control method struggles to accurately match the actual exhaust state within the coil insulation layer and cannot dynamically adjust the heating power based on impedance changes in the exhaust channels. This easily leads to a mismatch between heating power and exhaust capacity, ultimately resulting in the vacuum drying process for electrical coils failing to achieve ideal efficiency and product yield. Summary of the Invention

[0004] To address the technical problem of vacuum drying equipment struggling to balance drying efficiency and product quality, the present invention aims to provide a fully automatic continuous vacuum drying device and method for electrical coils. The specific technical solution adopted is as follows: Firstly, a fully automatic vacuum continuous drying device for electrical coils is provided, comprising: a data sensing unit for applying a basic heating current and a periodic detection current to the electrical coil, simultaneously acquiring heating power data of the electrical coil and air pressure data of the vacuum chamber, and extracting heating power fluctuation and chamber air pressure response quantities that are in sync with the periodic detection current from the heating power data and air pressure data; a flow resistance characteristic calculation unit for determining a flow resistance characteristic index based on the heating power fluctuation and chamber air pressure response quantities, the flow resistance characteristic index being used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer; a state evaluation unit for determining the flow resistance characteristic change rate based on the flow resistance characteristic index, the flow resistance characteristic change rate being used to characterize the degree of deviation of the current exhaust channel from the initial state; and a closed-loop feedback unit for controlling the basic heating current to increase when the flow resistance characteristic change rate is less than or equal to a preset threshold, and controlling the basic heating current to decrease when the flow resistance characteristic change rate is greater than the preset threshold.

[0005] Secondly, a fully automatic vacuum continuous drying method for an electrical coil is provided. This method includes: applying a basic heating current and a periodic detection current to the electrical coil; simultaneously acquiring heating power data of the electrical coil and air pressure data of the vacuum chamber; and extracting heating power fluctuations and chamber air pressure responses that are in sync with the periodic detection current from the heating power data and air pressure data; determining a flow resistance characteristic index based on the heating power fluctuations and chamber air pressure responses, the flow resistance characteristic index being used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer; determining a flow resistance characteristic change rate based on the flow resistance characteristic index, the flow resistance characteristic change rate being used to characterize the degree of deviation of the current exhaust channel from its initial state; controlling the basic heating current to increase when the flow resistance characteristic change rate is less than or equal to a preset threshold; and controlling the basic heating current to decrease when the flow resistance characteristic change rate is greater than the preset threshold.

[0006] In one possible design, a base heating current and a periodic detection current are applied to the electrical coil, and heating power data of the electrical coil and air pressure data of the vacuum chamber are collected simultaneously. This includes: controlling the heating power supply to output a base heating current, and superimposing the periodic detection current on the base heating current to form a composite excitation current; the periodic detection current adopts a sinusoidal waveform, the frequency of the periodic detection current is determined according to the thermal capacitance characteristics of the electrical coil and the environmental drift characteristics of the vacuum chamber, and the amplitude of the periodic detection current is determined according to the base heating current and a preset ratio; the output voltage and output current of the heating power supply are collected simultaneously, as well as the vacuum gauge signal installed on the side wall of the vacuum chamber; the heating power data is determined according to the output voltage and output current, and the air pressure data is determined according to the vacuum gauge signal.

[0007] In one possible design, the heating power fluctuation and cavity pressure response, which are at the same frequency as the periodic probe current, are extracted from the heating power data and pressure data. This includes: performing linear detrending processing on the heating power data and pressure data within a preset detection period to eliminate DC baseline and low-frequency environmental drift. The detection period is a preset sliding time window, and the length of the sliding time window is set to an integer multiple of the periodic probe current period. The detrending data is then correlated with a reference signal at the same frequency as the periodic probe current to obtain the heating power fluctuation and cavity pressure response.

[0008] In one possible design, before applying the basic heating current and periodic detection current to the electrical coil, the fully automatic vacuum continuous drying method for the electrical coil further includes: starting the vacuum unit to evacuate the vacuum chamber, and continuously collecting chamber pressure data for a preset duration while the basic heating current is zero; and determining the standard deviation of the collected chamber pressure data as the preset no-load pressure fluctuation threshold.

[0009] In one possible design, before determining the flow resistance characteristic index, the fully automatic vacuum continuous drying method for the above-mentioned electrical coil further includes: determining the current standard deviation of the cavity air pressure response in the current detection cycle; if the current standard deviation is less than the preset no-load air pressure fluctuation threshold, determining that the current detection cycle is an invalid response state, and setting the flow resistance characteristic index to a preset value indicating no exhaust occurs.

[0010] In one possible design, the flow resistance characteristic index is determined based on the heating power fluctuation and the cavity pressure response, including: determining the current detection cycle as an effective response state when the current standard deviation is greater than or equal to a preset no-load pressure fluctuation threshold; in the effective response state, constructing a two-dimensional hysteresis trajectory based on the heating power fluctuation and the cavity pressure response, with the heating power fluctuation as the horizontal axis and the cavity pressure response as the vertical axis; determining the pressure response intensity based on the regression slope of the two-dimensional hysteresis trajectory, which characterizes the amplitude of external pressure fluctuation excited by a unit heating power fluctuation; determining the pressure hysteresis based on the closed area of ​​the two-dimensional hysteresis trajectory, which characterizes the time effect of gas being impeded inside the insulation layer; and determining the flow resistance characteristic index based on the pressure hysteresis and the pressure response intensity.

[0011] In one possible design, the flow resistance characteristic change rate is determined based on the flow resistance characteristic index, including: determining the average of multiple flow resistance characteristic indices determined in the initial stage of drying as a temporary reference value; if the temporary reference value is within a preset empirical safety range, determining the temporary reference value as the initial flow resistance reference value; and determining the deviation ratio of the flow resistance characteristic index determined in real time relative to the initial flow resistance reference value as the flow resistance characteristic change rate.

[0012] In one possible design, controlling the increase of the base heating current includes: linearly increasing the base heating current with a preset fixed step size until the base heating current reaches a preset maximum allowable current; controlling the decrease of the base heating current includes: using the value of the rate of change of the current resistance characteristic as a penalty gain to exponentially decay the base heating current to obtain an adjusted current value, wherein the larger the value of the rate of change of the current resistance characteristic, the faster the rate of decrease of the base heating current; and determining the preset minimum holding current as the base heating current when the adjusted current value is less than the preset minimum holding current.

[0013] In one possible design, the fully automatic vacuum continuous drying method for the aforementioned electrical coil further includes: acquiring the current air pressure data of the vacuum chamber, the standard deviation of the chamber air pressure response within the current detection cycle, and the current basic heating current; and determining that the drying process of the electrical coil is completed and cutting off the basic heating current when the current air pressure data is less than or equal to the process endpoint threshold, the standard deviation of the chamber air pressure response is less than the preset no-load air pressure fluctuation threshold, and the difference between the current basic heating current and the preset maximum allowable current is less than or equal to the preset current tolerance.

[0014] The present invention has the following beneficial effects: In the fully automatic vacuum continuous drying equipment and drying method for electrical coils provided by this invention, a complete automated system from signal excitation, feature extraction, state evaluation to closed-loop control is constructed by setting up a data sensing unit, a flow resistance feature calculation unit, a state evaluation unit, and a closed-loop feedback unit. The equipment uses the data sensing unit to apply a composite excitation, including a basic heating current and a periodic detection current, to the electrical coil, and extracts the heating power fluctuation and cavity pressure response at the same frequency as the detection current, thereby mapping the microscopic exhaust state inside the insulation layer into a measurable external signal. Further, the flow resistance feature calculation unit determines the flow resistance feature index based on the aforementioned fluctuation and response, which comprehensively reflects the impedance state of the exhaust channel. The state evaluation unit determines the flow resistance feature change rate based on the flow resistance feature index to quantify the deviation of the current exhaust state from the initial state. Finally, the closed-loop feedback unit controls the basic heating current to increase or decrease in an asymmetric manner based on the comparison result of the flow resistance feature change rate and a preset threshold. This system achieves indirect perception and quantitative characterization of the microscopic exhaust state deep within the insulation layer, transforming the unmeasurable risk of internal airlock into a calculable rate of change in flow resistance characteristics. Based on this, it dynamically matches heat input with the medium's permeability. When exhaust is unobstructed, the heating current is gradually increased to approach the drying efficiency limit; when airlock precursors are detected, the heating current is rapidly reduced to avoid the risk of bubbling. This adaptive control mechanism based on internal state feedback fundamentally solves the inefficiency problem caused by the conservative heating strategies employed in traditional processes to ensure quality. It significantly shortens the drying cycle while ensuring product yield, achieving synergistic optimization of drying efficiency and product quality. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the structure of a fully automatic vacuum continuous drying device for electrical coils provided in one embodiment of the present invention; Figure 2 This is a schematic flowchart of a fully automatic vacuum continuous drying method for electrical coils provided in one embodiment of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a fully automatic vacuum continuous drying device and drying method for electrical coils proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] In embodiments of the present invention, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0019] In the description of this invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, "at least one" and "more than one" refer to two or more. The terms "first," "second," etc., do not limit the quantity or order of execution, and "first," "second," etc., do not necessarily imply differences.

[0020] Unless otherwise defined, 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 pertains.

[0021] The following description, in conjunction with the accompanying drawings, details the specific scheme of a fully automatic vacuum continuous drying device and drying method for electrical coils provided by the present invention.

[0022] Please see Figure 1 The diagram shows a structural schematic of a fully automatic vacuum continuous drying device for electrical coils according to an embodiment of the present invention. The fully automatic vacuum continuous drying device 10 for electrical coils includes a data sensing unit 11, a flow resistance characteristic calculation unit 12, a state evaluation unit 13, and a closed-loop feedback unit 14.

[0023] The data sensing unit 11 is used to apply a basic heating current and a periodic detection current to the electrical coil, simultaneously collect the heating power data of the electrical coil and the air pressure data of the vacuum chamber, and extract the heating power fluctuation and chamber air pressure response that are in the same frequency as the periodic detection current from the heating power data and air pressure data.

[0024] In some embodiments, the data sensing unit 11 first controls the heating power supply to output a basic heating current, and superimposes a periodic detection current onto the basic heating current to form a composite excitation current. The periodic detection current uses a sinusoidal waveform, its frequency is determined based on the thermal capacitance characteristics of the electrical coil and the environmental drift characteristics of the vacuum cavity, and its amplitude is determined based on the basic heating current and a preset ratio. Simultaneously with the excitation, the data sensing unit 11 synchronously acquires the output voltage and current of the heating power supply, as well as the signal from a vacuum gauge installed on the sidewall of the vacuum cavity. It determines the heating power data based on the output voltage and current, and the air pressure data based on the vacuum gauge signal. Further, the data sensing unit 11 performs linear detrending processing on the heating power data and air pressure data within a preset detection period to eliminate DC baseline and low-frequency environmental drift. The detrending data is then correlated with a reference signal having the same frequency as the periodic detection current, thereby separating the pure heating power fluctuation and cavity air pressure response from the noisy signal. The detection period is a preset sliding time window, the length of which is set to an integer multiple of the periodic detection current period. The heating power fluctuation and cavity air pressure response extracted by the data sensing unit 11 will be sent to the flow resistance feature calculation unit 12 for further analysis.

[0025] The flow resistance characteristic calculation unit 12 is used to determine the flow resistance characteristic index based on the heating power fluctuation and the cavity air pressure response. The flow resistance characteristic index is used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer.

[0026] In some embodiments, before determining the flow resistance characteristic index, the flow resistance characteristic calculation unit 12 first determines whether the current detection cycle is a valid response state. Specifically, the flow resistance characteristic calculation unit 12 calculates the current standard deviation of the cavity pressure response within the current detection cycle and compares it with a pre-calibrated preset no-load pressure fluctuation threshold. The preset no-load pressure fluctuation threshold is determined by the data sensing unit 11 through a no-load calibration step before applying excitation: the vacuum unit is started to evacuate the vacuum cavity, and cavity pressure data is continuously collected for a preset duration while the basic heating current is zero. The standard deviation of the cavity pressure data during this period is determined as the preset no-load pressure fluctuation threshold. If the current standard deviation is less than the preset no-load pressure fluctuation threshold, the current detection cycle is determined to be an invalid response state, and the flow resistance characteristic calculation unit 12 directly sets the flow resistance characteristic index to a preset value indicating no exhaust occurs. If the current standard deviation is greater than or equal to the preset no-load pressure fluctuation threshold, the current detection cycle is determined to be a valid response state, and the flow resistance characteristic index calculation process begins. Under effective response conditions, the flow resistance characteristic calculation unit 12 constructs a two-dimensional hysteresis trajectory based on the heating power fluctuation and the cavity gas pressure response. The two-dimensional hysteresis trajectory has the heating power fluctuation as the horizontal axis and the cavity gas pressure response as the vertical axis. Subsequently, the flow resistance characteristic calculation unit 12 determines the gas pressure response intensity based on the regression slope of the two-dimensional hysteresis trajectory. The gas pressure response intensity is used to characterize the amplitude of the external gas pressure fluctuation excited by a unit heating power fluctuation. The gas pressure hysteresis is determined based on the closed area of ​​the two-dimensional hysteresis trajectory. The gas pressure hysteresis is used to characterize the time effect of gas being impeded inside the insulation layer. Finally, the flow resistance characteristic index is determined based on the ratio of the gas pressure hysteresis to the gas pressure response intensity. The calculated flow resistance characteristic index will be sent to the state assessment unit 13.

[0027] The state assessment unit is used to determine the rate of change of flow resistance characteristics based on the flow resistance characteristic index, wherein the rate of change of flow resistance characteristics is used to characterize the degree of deviation of the current exhaust channel from the initial state.

[0028] In some embodiments, at the initial stage of the drying process, the state assessment unit 13 receives multiple flow resistance characteristic indices output by the flow resistance characteristic calculation unit 12 in real time, and determines the average of these flow resistance characteristic indices as a temporary reference value. If the temporary reference value is within a preset empirical safety range, the state assessment unit 13 locks the temporary reference value as the initial flow resistance reference value, which remains unchanged during the current drying process. In subsequent drying processes, the state assessment unit 13 receives the flow resistance characteristic index of the current detection cycle in real time and calculates its deviation ratio relative to the initial flow resistance reference value, determining this deviation ratio as the flow resistance characteristic change rate. The flow resistance characteristic change rate is a core indicator for measuring the current airflow smoothness of the insulation layer and will be sent to the closed-loop feedback unit 14 as the basis for feedback control.

[0029] The closed-loop feedback unit controls the basic heating current to increase when the rate of change of the flow resistance characteristic is less than or equal to a preset threshold, and controls the basic heating current to decrease when the rate of change of the flow resistance characteristic is greater than the preset threshold.

[0030] In some embodiments, when the closed-loop feedback unit 14 performs an increment operation, it linearly increases the base heating current with a preset fixed step size until the base heating current reaches a preset maximum allowable current. When the closed-loop feedback unit 14 performs a decrement operation, it uses the value of the rate of change of the current resistance characteristic as a penalty gain to exponentially decay the base heating current. The larger the value of the rate of change of the current resistance characteristic, the faster the base heating current decreases. At the same time, to prevent the detection signal from disappearing due to excessively low current, if the adjusted base heating current is less than the preset minimum holding current, the closed-loop feedback unit 14 clamps the base heating current to the preset minimum holding current. The adjusted base heating current is fed back to the data sensing unit 11 for excitation application in the next cycle, thereby forming a complete closed-loop control link. In addition, the closed-loop feedback unit 14 is also responsible for determining the drying endpoint. It acquires the current air pressure data of the vacuum chamber, the standard deviation of the chamber air pressure response in the current detection cycle, and the current basic heating current. If the current air pressure data is less than or equal to the process endpoint threshold, the standard deviation of the chamber air pressure response is less than the preset no-load air pressure fluctuation threshold, and the difference between the current basic heating current and the preset maximum allowable current is less than or equal to the preset current tolerance, it determines that the drying process of the electrical coil is completed and cuts off the basic heating current.

[0031] Please see Figure 2 The diagram illustrates a process flow chart of a fully automatic vacuum continuous drying method for an electrical coil according to an embodiment of the present invention, including the following steps S201-S205.

[0032] S201. Apply a basic heating current and a periodic detection current to the electrical coil, and simultaneously collect the heating power data of the electrical coil and the air pressure data of the vacuum chamber.

[0033] In some embodiments, the programmable DC heating power supply is controlled to output a set basic heating current to the electrical coil. Meanwhile, in the basic heating current Periodic probe current with superimposed sine wave This generates a composite excitation current applied to the electrical coil to disrupt the thermal equilibrium of the insulation layer, thereby stimulating a pressure response within the insulation layer. The global time of equipment operation is defined as the continuous time axis characterizing the entire drying process, with periodic current detection. The frequency is determined based on the thermal capacitance filtering characteristics of the electrical coil and the ambient temperature drift characteristics of the vacuum chamber, and is set as a preset low-frequency band (too high a frequency will be filtered out by the thermal capacitance of the stator core, and too low a frequency will be easily affected by ambient temperature drift). An example selectable range is 0.1Hz to 0.5Hz, such as 0.2Hz, with the amplitude based on the basic heating current. A preset ratio (e.g., 1% to 2% of the base heating current) is used to ensure that the main heating process is not significantly affected while triggering a detectable gas pressure response.

[0034] While applying excitation, a multi-channel data acquisition card equipped with the same hardware clock source is used as the synchronous trigger reference to synchronously acquire real-time analog signals from two channels. The first channel is the real-time output voltage signal from the programmable DC heating power supply. and real-time output current signal The second channel is a vacuum gauge signal for the real-time air pressure of the vacuum chamber, detected by a high-response vacuum gauge installed on the side wall of the vacuum chamber. Furthermore, it is ensured that the acquisition time alignment error of the two channels of analog signals is less than a preset time threshold (e.g., 1ms) to ensure the accurate phase relationship between heating power and gas pressure response in subsequent analysis.

[0035] Furthermore, based on the acquired real-time output voltage signal... and real-time output current signal The real-time heating power data of the electrical coil is obtained through product operation. , , To characterize the heating power data of the real-time thermal energy input of the electrical coil, the acquired real-time vacuum chamber pressure signal is converted into digital real-time vacuum chamber pressure data through analog-to-digital conversion. The synchronous acquisition of heating power data from the electrical coil and air pressure data from the vacuum chamber was completed, and the acquired heating power data... and air pressure data This serves as the raw physical data for subsequent extraction of frequency fluctuations and response quantities.

[0036] In some embodiments, a no-load calibration step is first performed to determine the system’s noise floor level before applying the base heating current and periodic probe current to the electrical coil.

[0037] First, the vacuum detection component of the vacuum drying system is adapted and configured to match the vacuum chamber. A vacuum gauge with resolution and responsiveness that meets the requirements for capturing transient pressure fluctuations is used to detect the air pressure in the vacuum chamber. The vacuum chamber is set to a low volume ratio structure to reduce signal attenuation caused by gas diffusion. After the configuration is completed, the vacuum unit is started to evacuate the vacuum chamber until the chamber pressure reaches the basic vacuum range set by the process. During this process, the basic heating current is kept at zero, so that the basic heating current output to the electrical coil remains at zero.

[0038] During this process, at a preset sampling frequency (e.g., 100Hz) The raw gas pressure data of the vacuum chamber is continuously acquired for a preset duration (e.g., 60 seconds) as specified in the process calibration, to obtain the raw chamber gas pressure data sequence within the calibration duration. ,in The global time of system operation represents the continuous time axis of the entire drying process. This refers to the sampling point number of the original cavity air pressure data. , This represents the total number of sampling points within the preset time period.

[0039] Further analysis of the acquired raw cavity air pressure data sequence The average value of the original cavity air pressure data was obtained by performing mean calculation. Furthermore, based on the original cavity air pressure data sequence and average Calculate the standard deviation of the original cavity air pressure data, and determine this standard deviation as the preset no-load air pressure fluctuation threshold. ,in, The air pressure fluctuation threshold, which characterizes the background noise level of the vacuum drying equipment, is stored in the memory of the system controller. It provides a noise threshold for the validity determination of the cavity air pressure response during subsequent detection cycles, and also serves as the core reference benchmark for the drying endpoint determination process.

[0040] S202. Extract the heating power fluctuation and cavity pressure response from the heating power data and air pressure data, which are in sync with the periodic detection current.

[0041] As one possible implementation, a preset detection period is first set as a sliding time window for the detection current of the adaptation period, and the length of the sliding time window is denoted as... It is strictly set to be a positive integer multiple of the period of the periodic probe current, and its formula is expressed as follows: ,in, It is a positive integer, used to avoid spectral leakage errors caused by non-integer period truncation, for example, taking The preset detection period is 3 times the period of the detection current. The frequency of the periodic probe current.

[0042] Furthermore, the drying process is divided into detection cycles using a sliding time window as the unit. For the first... Each testing cycle, for each testing cycle Internal heating power data and air pressure data Linear detrending processing is performed separately, where The global operating time of the equipment is represented by a continuous time axis characterizing the entire drying process. The least squares method is used to linearly fit the heating power data and air pressure data within the detection period, obtaining their respective fitted lines. Then, the original heating power data and original air pressure data are subtracted from their corresponding fitted lines to eliminate the influence of DC baseline and low-frequency environmental drift, resulting in detrended heating power data. and detrended air pressure data .

[0043] Subsequently, a digital bandpass filter is used to extract the component with the same frequency as the periodic probe current. Optionally, a narrowband digital bandpass filter is designed, with its center frequency set to the frequency of the periodic probe current. The passband width is set according to the actual noise level (e.g., set to...). This effectively filters out out-of-band noise, retaining only the signal component with the same frequency as the probe current. The de-stressed heating power data... The input is filtered by the bandpass filter, and the resulting output sequence is the heating power fluctuation sequence with the same frequency as the periodic probe current. ,in For each detection cycle The sampling point number within, It is a positive integer. Similarly, the detrended air pressure data... By inputting the same bandpass filter, the corresponding cavity pressure response sequence is obtained. To ensure accurate phase relationship between heating power and gas pressure response, both sets of data were filtered using the same filter parameters to ensure consistent phase delay. Through this bandpass filtering, even if the effective signal amplitude is below the noise floor, a clear same-frequency response waveform can be extracted from a strong noise background. and All of them retain the time-domain sequence form that corresponds one-to-one with the original sampling time.

[0044] S203. Determine the flow resistance characteristic index based on the heating power fluctuation and the cavity air pressure response.

[0045] Among them, the flow resistance characteristic index is used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer.

[0046] As one possible approach, it is first determined whether the current detection cycle is in an effective response state to ensure that subsequent calculations are based on actual exhaust activity rather than the equipment's background noise.

[0047] In some embodiments, the cavity pressure response sequence extracted within the current detection period is assumed to be: Its current standard deviation is The current standard deviation Compared with the preset no-load air pressure fluctuation threshold For comparison, among them This is the detection cycle number. It is a positive integer. For the first The sampling point sequence number within each detection cycle, It is a positive integer. For the first Within the first detection cycle Cavity air pressure response at each sampling point The threshold for no-load air pressure fluctuation is used to characterize the background noise level of the equipment; if Less than The current detection cycle is determined to be in an invalid response state, and the flow resistance characteristic index is set. Set to a preset value representing no exhaust (e.g., an empirical value of zero), and skip the subsequent calculation of the flow resistance characteristic change rate to avoid numerical instability caused by the denominator approaching zero; if Greater than or equal to The current detection cycle is determined to be in an effective response state based on the heating power fluctuation. and cavity air pressure response Conduct flow resistance characteristic index The solution, where For the first Within the first detection cycle Heating power fluctuation at each sampling point.

[0048] Furthermore, under effective response conditions, the heating power fluctuation is considered. The horizontal axis represents the cavity air pressure response. Using the vertical axis, construct the first The two-dimensional hysteresis trajectory within a detection cycle typically forms a closed hysteresis loop, and its geometric characteristics reflect the resistance characteristics of the exhaust channel within the insulation layer. Furthermore, based on the trajectory point set of the two-dimensional hysteresis trajectory... Calculate the air pressure response intensity Pressure response intensity The pressure response intensity is used to characterize the amplitude of the pressure fluctuation induced by a unit heating power fluctuation. Linear regression analysis can be performed on the set of trajectory points to find an optimal fitted line that minimizes the sum of the squared distances from all trajectory points to that line.

[0049] In some embodiments, the formula for calculating the pressure response intensity, based on the least squares principle, is as follows: In the formula, For the first Total number of sampling points within a detection cycle For the first Heating power fluctuation within each detection cycle The arithmetic mean, For the first Cavity air pressure response within each detection cycle The arithmetic mean, It is a very small positive number, and an empirical value of 0.0001 can be taken to prevent the denominator from being zero. For the first The pressure response intensity per detection cycle. When exhaust is unobstructed. right The response is sensitive. right They show a strong positive correlation, and the regression slope is... The response amplitude is relatively large; when exhaust is obstructed, the response amplitude decreases. right The correlation decreased. The corresponding decrease.

[0050] The closed area of ​​the two-dimensional hysteresis trajectory is then calculated using the Discrete Green's Theorem, and the absolute value is taken to ensure the non-negativity of the area. The closed area is denoted as . Its formula is expressed as To eliminate the influence of signal amplitude on area, the closed area is then... After normalization, the pressure hysteresis is obtained. Its formula is expressed as ,in, For the first Heating power fluctuation within each detection cycle standard deviation For the first Cavity air pressure response within each detection cycle standard deviation It is a very small positive number, and an empirical value of 0.0001 can be taken to prevent the denominator from being zero. For the first The pressure hysteresis of each detection cycle is used to characterize the phase hysteresis effect caused by the gas being trapped inside the insulation layer. When an airlock forms inside, the phase hysteresis of the pressure response waveform relative to the heating power waveform increases, and the hysteresis loop area expands. The corresponding increase.

[0051] Finally, based on the pressure hysteresis With pressure response intensity Determine the flow resistance characteristic index.

[0052] In some embodiments, the formula for determining the flow resistance characteristic index is as follows: In the formula, It is the dynamic numerical stability constant. , An empirical coefficient (e.g., a value of 0.1) is used to match the equipment's inherent noise level. Used to ensure the strength of the air pressure response. Because the denominator remains at a base value equivalent to the environmental noise level even when the noise level is severely congested, this prevents the calculation results from diverging. For the first The flow resistance characteristic index for each detection cycle is used to characterize the impedance state of the exhaust channel in the insulation layer of the electrical coil. When exhaust is unobstructed, Smaller and Larger Maintain at a low level; when congestion occurs, Increase Decrease, the two inversely changing leads to The exponential increase significantly enhances the quantification sensitivity of the exhaust channel impedance state.

[0053] It should be noted that the air pressure response intensity Physically, it should be a positive value, but in actual measurements, it may appear negative due to noise interference or phase anomalies. To ensure the stability and correctness of the flow resistance characteristic index calculation, [further details are needed]. Take the absolute value and process it. It characterizes the magnitude of the pressure fluctuation caused by a unit heating power fluctuation.

[0054] S204. Determine the rate of change of flow resistance characteristics based on the flow resistance characteristic index.

[0055] Among them, the rate of change of flow resistance characteristics is used to characterize the degree of deviation of the current exhaust passage from the initial state.

[0056] As one possible approach, a reliable reference benchmark is first established at the initial stage of the drying process to eliminate the impact of individual differences between different coils and equipment state drift on subsequent judgments.

[0057] In some embodiments, during the initial drying phase (e.g., the first 60 seconds after heating begins), the device receives in real time multiple flow resistance characteristic indices determined based on step S203 described above. ,in This indicates the sequence number of the detection cycle. All non-zero valid values ​​of these flow resistance characteristic indices are stored in a buffer. When the preset reference locking time is reached (the end time of the initial drying stage), the arithmetic mean of the data in the buffer is calculated to obtain a temporary reference value.

[0058] For example, the non-zero flow resistance characteristic index determined in the initial stage of drying. total If there are one, then the temporary benchmark value Temporary benchmark value Used to characterize the basic impedance state of the exhaust channel of the insulation layer during the initial stage of drying.

[0059] Furthermore, to ensure that the learned reference value can truly reflect the normal state of the coil rather than abnormal moisture or blockage, the temporary reference value needs to be verified for safety.

[0060] In some embodiments, the calculated temporary baseline value The data is compared and verified with the pre-stored preset experience safety range, which is: ,in This is the lower limit of a preset safety range based on experience, for example, a value of 0.3. This is the upper limit of the preset empirical safety range, such as a value of 0.5. Both are threshold values ​​of the flow resistance characteristic index preset based on the characteristics of the electrical coil insulation layer and the equipment operating parameters; if In Within the range, if the baseline value verification is passed, the temporary baseline value will be set. Locked to the initial flow resistance reference value ;like Exceeding If the reference value verification fails, the control device will operate under a safe current for a preset stabilization time (e.g., 60 seconds), and the average value of the flow resistance characteristic index during this period will be forcibly locked as the initial flow resistance reference value. Alternatively, a preset empirical default value (which can be set to a fixed value in the range of 0.3 to 0.5, such as 0.4) can be used as the initial flow resistance reference value. At the same time, the maximum subsequent heating current is limited (e.g., reduced to 50% of the rated value) to prevent control risks due to reference failure. Initial flow resistance reference value. Once locked, it remains unchanged throughout the entire drying process, serving as a reference zero point for subsequent judgments on changes in flow resistance.

[0061] Finally, after the baseline is locked, the system enters the real-time status evaluation stage, and the deviation ratio of the real-time determined flow resistance characteristic index relative to the initial flow resistance baseline value is determined as the flow resistance characteristic change rate.

[0062] In some embodiments, for each new detection cycle Real-time acquisition of the calculated flow resistance characteristic index And calculate its value relative to the initial flow resistance reference value. The deviation ratio is determined as the characteristic change rate of flow resistance. Determine the characteristic rate of change of flow resistance The calculation formula is as follows: in, For the current number The rate of change of flow resistance characteristics over each detection cycle is used to characterize the degree of impedance deviation of the current electrical coil insulation venting channel relative to its initial state. If This indicates that the current flow resistance characteristic index is less than or equal to the initial baseline, suggesting that the exhaust passage remains unobstructed or in a better condition than at the initial moment, possessing the potential to accommodate higher heat input; if This indicates that the current flow resistance characteristic index exceeds the initial baseline, suggesting an increase in internal exhaust resistance and the beginning of signs of airlock formation. The higher the value, the more severe the blockage.

[0063] It should be noted that the initial flow resistance reference value It is a non-zero positive value determined through no-load calibration during the initial stage of drying; specifically, it is a temporary reference value. Lock it as when it is within the preset safety range. Alternatively, when the temporary baseline value is abnormal, a preset empirical default value can be used as the reference. Regardless of the method used, the determined All values ​​are greater than zero, so the denominator of this calculation formula is never zero, ensuring the mathematical validity and physical meaning of the calculation of the flow resistance characteristic change rate.

[0064] S205. When the rate of change of flow resistance characteristics is less than or equal to a preset threshold, control the basic heating current to increase; when the rate of change of flow resistance characteristics is greater than the preset threshold, control the basic heating current to decrease.

[0065] It should be noted that the preset threshold The value can be preset according to process requirements. For example, it can be set to 0, which means that the initial flow resistance reference value is the boundary, and a value greater than 0 is considered to indicate a blocking trend; or it can be set to a small positive number based on experience to allow for normal fluctuations within a certain range.

[0066] As one possible implementation, in the characteristic rate of change of flow resistance Less than or equal to the preset threshold In this case, it is determined that the current exhaust passage is unobstructed and there is room to further increase the heating power, so the basic heating current is controlled to increase incrementally.

[0067] In some embodiments, a preset fixed step size is used. For the previous testing cycle Basic heating current Perform a linear boost to obtain the current detection cycle. Basic heating current Its formula is expressed as ,in, The preset maximum allowable current is determined by the coil's rated parameters and safety margin; for example, it can be set to 80%-90% of the coil's rated current. The increment is a fixed step size, which can be taken as an empirical value of 1A, or dynamically adjusted according to the heating stage. This indicates a minimum value operation, used to ensure that the incremented base heating current does not exceed the preset maximum allowable current. This ensures the safe operation of the equipment.

[0068] The rate of change of flow resistance characteristics Greater than the preset threshold When the empirical value is 0, it is determined that there are signs of gas lock forming inside the electrical coil. Gas production must be suppressed immediately to avoid damage to the insulation layer. Therefore, the basic heating current is controlled to decrease.

[0069] In some embodiments, controlling the decrease of the base heating current can employ an exponential decay strategy, using the value of the rate of change of the flow resistance characteristic as a penalty gain to rapidly suppress the set current value of the previous detection cycle. The calculation formula is as follows: In the formula, To adjust the sensitivity coefficient and control the attenuation intensity, it can be preset according to the coil type and process requirements, for example, a value of 5.0; This represents the rate of change of the current resistance characteristic. The larger the value, the larger the denominator, and the faster the current decreases, thus achieving the asymmetric control effect of "the more severe the blockage, the faster the current decreases." For the previous testing cycle Basic heating current, This is the initial adjusted current value corresponding to the current detection cycle.

[0070] It should be noted that the decreasing operation shown in the above calculation formula only applies to the rate of change of flow resistance characteristic. Greater than the preset threshold Execution is performed under certain conditions, while a preset threshold is used. Since the value is non-negative (e.g., it can be set to 0), when a decrement operation is performed, it must satisfy the condition. At the same time, adjust the sensitivity coefficient. Let the denominator be a pre-defined positive real number. Therefore, the denominator of the formula... From positive number 1 and positive number The sum of these terms is always greater than 1, ensuring that the denominator is never zero, thus guaranteeing the numerical stability of the current regulation calculation.

[0071] Furthermore, to prevent the detection signal from disappearing due to excessive current reduction, which could lead to control logic deadlock, the drying equipment is also equipped with a clamping protection mechanism. (The last sentence appears to be incomplete and unrelated to the preceding text. It likely refers to a different device or system.) Greater than or equal to the preset minimum holding current In this case, the adjusted current value Determine the basic heating current After adjustment of the current value Less than the preset minimum holding current In this case, the minimum holding current will be preset. Determine the basic heating current Its formula is expressed as Among them, the preset minimum holding current For example, it can be set to 10% of the coil's rated current to ensure that even in a severe blockage, the coil still has a reference heat source capable of generating a detectable signal, so that the system can sense and restore the current rise as soon as the blockage is relieved.

[0072] Furthermore, the basic heating current obtained after the above adjustments The data is fed back to the data sensing unit 11 for excitation application in the next detection cycle, thus forming a complete closed-loop control link. Through an asymmetric adjustment strategy based on the rate of change of flow resistance characteristics, the system can dynamically match the real-time exhaust capacity of the insulation layer, maximize heat input to shorten the drying cycle when exhaust is smooth, and rapidly reduce flow to eliminate the risk of foaming when blockage occurs, thus achieving synergistic optimization of drying efficiency and product quality.

[0073] In some embodiments, when determining whether the drying process of the electrical coil is complete, a multi-dimensional interlocking endpoint determination logic is executed to ensure that the drying process is terminated only when the moisture is completely drained and there is no risk of blockage, thereby avoiding the risk of misjudging the drying process as complete due to severe blockage causing no gas to be discharged.

[0074] Optionally, three sets of key status data are first acquired: the first set is the current air pressure data of the vacuum chamber collected in real time. The second set represents the standard deviation of the cavity pressure response calculated within the current detection period. This standard deviation is based on the sequence of cavity pressure response extracted within the current detection period. The calculations show that the third set value is the basic heating current setpoint applied to the electrical coil at the current moment. .

[0075] Then, the three sets of data were compared with the corresponding preset conditions: First, determine the current air pressure data. Is it less than or equal to the process endpoint threshold? Process endpoint threshold It can be preset according to process requirements. For example, it can be set to 50Pa, which means that when the cavity pressure drops to this level, it indicates that the macroscopic vacuum environment has reached the physical conditions for drying.

[0076] Second, determine the standard deviation of the cavity pressure response. Is it less than the preset no-load air pressure fluctuation threshold? Preset no-load air pressure fluctuation threshold The system background noise level was determined during the no-load calibration phase before drying began. This indicates that even with the heating excitation of the periodic probe current, no effective gas is discharged, meaning that gas production at the microscopic level has essentially ceased.

[0077] Third, determine the current basic heating current. With the preset maximum allowable current Is the difference less than or equal to the preset current tolerance? That is, whether it satisfies Preset maximum allowable current The current tolerance is preset according to the rated parameters and safety margin of the electrical coil. For example, it can be set to The 1%-5% threshold is used to determine whether the current has recovered and stabilized near the maximum allowable current. If severe blockage prevents gas discharge, the flow resistance characteristic index will remain high, triggering an exponential current reduction mechanism to suppress the current at a low level. In this case, the condition will not be met. Only when venting is unobstructed and flow resistance is normal can the current be increased to the maximum allowable current through a linear current increase strategy. Therefore, in Under these circumstances, it is currently in a "full heating" state.

[0078] When all three conditions above are met, that is , and When the timer is set, a timer with a preset monitoring duration is started, for example, continuously monitoring for 300 seconds. If all three conditions are met within the preset monitoring duration, the drying process of the electrical coil is determined to be complete, the heating power is automatically cut off, and the drying process ends. If any condition is no longer met during the timer period, the timer is reset, and the normal drying process continues.

[0079] In addition, to prevent the drying process from being indefinitely prolonged due to abnormal conditions such as vacuum unit failure or sensor malfunction, a maximum operating timeout fuse mechanism is also in place. If the heating time exceeds the preset absolute safety time limit (e.g., 4 hours) and the above interlocking conditions are not met, the system will be forcibly shut down and an alarm will be issued, prompting manual intervention for inspection.

[0080] Understandably, in the fully automatic vacuum continuous drying method for electrical coils provided in this embodiment of the invention, by applying a composite excitation including a basic heating current and a periodic detection current to the coil, and extracting the heating power fluctuation and cavity pressure response quantities with the same frequency as the detection current from the synchronously collected heating power data and cavity pressure data, accurate extraction of microscopic exhaust signals is achieved under strong noise background. This transforms the exhaust state inside the insulation layer, which cannot be directly measured, into a quantifiable external physical quantity. Furthermore, based on the aforementioned fluctuation and response quantities, a flow resistance characteristic index is determined. This index comprehensively reflects the impedance state of the exhaust channel, providing a reliable quantitative basis for subsequent control. Then, based on the flow resistance characteristic index, a flow resistance characteristic change rate, representing the degree of deviation of the current exhaust state from the initial state, is determined, establishing a real-time state evaluation mechanism. Finally, based on the comparison result of the flow resistance characteristic change rate and a preset threshold, the basic heating current is controlled to increase or decrease in an asymmetric manner. Through the organic coordination of the above steps, this method constructs a complete adaptive control process from signal excitation, feature extraction, state evaluation to closed-loop feedback, realizing real-time perception and proactive avoidance of the risk of airlock inside the insulation layer. This invention dynamically adjusts the heating strategy based on real-time changes in the internal exhaust status. When the rate of change in flow resistance characteristics indicates smooth exhaust, the current is actively increased to improve drying efficiency. When signs of impending airlock are detected, the current is immediately reduced to prevent damage to the insulation layer. This fundamentally solves the inefficiency problem caused by the conservative heating strategy forced to be adopted in traditional processes to ensure quality, achieving a balance between drying efficiency and product quality. Simultaneously, this method transforms the microscopic physical state into calculable characteristic indicators for closed-loop control, eliminating reliance on manual experience and fixed process curves, significantly improving batch processing consistency and process reliability.

[0081] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0082] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A fully automatic vacuum continuous drying device for electrical coils, characterized in that, include: The data sensing unit is used to apply a basic heating current and a periodic detection current to the electrical coil, simultaneously collect the heating power data of the electrical coil and the air pressure data of the vacuum cavity, and extract the heating power fluctuation and cavity air pressure response that are in the same frequency as the periodic detection current from the heating power data and the air pressure data. The flow resistance characteristic calculation unit is used to determine the flow resistance characteristic index based on the heating power fluctuation and the cavity air pressure response. The flow resistance characteristic index is used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer. The state assessment unit is used to determine the flow resistance characteristic change rate based on the flow resistance characteristic index, wherein the flow resistance characteristic change rate is used to characterize the degree of deviation of the current exhaust channel from the initial state. The closed-loop feedback unit controls the basic heating current to increase when the rate of change of the flow resistance characteristic is less than or equal to a preset threshold, and controls the basic heating current to decrease when the rate of change of the flow resistance characteristic is greater than the preset threshold.

2. A fully automated vacuum continuous drying method for electrical coils, characterized in that, The method includes: A basic heating current and a periodic detection current are applied to the electrical coil, and the heating power data of the electrical coil and the air pressure data of the vacuum chamber are collected simultaneously. The heating power fluctuation and the chamber air pressure response, which are in the same frequency as the periodic detection current, are extracted from the heating power data and the air pressure data. The flow resistance characteristic index is determined based on the heating power fluctuation and the cavity air pressure response. The flow resistance characteristic index is used to characterize the impedance state of the exhaust channel of the electrical coil insulation layer. Based on the flow resistance characteristic index, the flow resistance characteristic change rate is determined, which is used to characterize the degree of deviation of the current exhaust channel from the initial state. When the rate of change of the flow resistance characteristic is less than or equal to a preset threshold, the basic heating current is controlled to increase; when the rate of change of the flow resistance characteristic is greater than the preset threshold, the basic heating current is controlled to decrease.

3. The fully automatic vacuum continuous drying method for electrical coils according to claim 2, characterized in that, A basic heating current and a periodic detection current are applied to the electrical coil, and the heating power data of the electrical coil and the air pressure data of the vacuum chamber are collected simultaneously, including: The heating power supply outputs the basic heating current, and the periodic detection current is superimposed on the basic heating current to form a composite excitation current; the periodic detection current adopts a sine waveform, the frequency of the periodic detection current is determined according to the thermal capacity characteristics of the electrical coil and the environmental drift characteristics of the vacuum cavity, and the amplitude of the periodic detection current is determined according to the basic heating current and a preset ratio. The output voltage and output current of the heating power supply are collected simultaneously, as well as the signal from the vacuum gauge installed on the side wall of the vacuum chamber. The heating power data is determined based on the output voltage and the output current, and the air pressure data is determined based on the vacuum gauge signal.

4. The fully automatic vacuum continuous drying method for electrical coils according to claim 2, characterized in that, Extracting the heating power fluctuation and cavity pressure response quantities that are in sync with the periodic detection current from the heating power data and the air pressure data includes: The heating power data and the air pressure data within the preset detection period are respectively subjected to linear detrending processing. The detection period is a preset sliding time window, and the length of the sliding time window is set to an integer multiple of the period of the periodic detection current. The data after detrending processing is correlated with a reference signal that has the same frequency as the periodic detection current to obtain the heating power fluctuation and the cavity air pressure response.

5. The fully automatic vacuum continuous drying method for electrical coils according to claim 2, characterized in that, Before applying the base heating current and the periodic detection current to the electrical coil, the method further includes: The vacuum unit is started to evacuate the vacuum chamber, and the chamber pressure data is continuously collected for a preset time while the basic heating current is zero. The standard deviation of the collected chamber pressure data is determined as the preset no-load pressure fluctuation threshold.

6. The fully automatic vacuum continuous drying method for electrical coils according to claim 5, characterized in that, Before determining the flow resistance characteristic index, the method further includes: Determine the current standard deviation of the cavity air pressure response during the current detection period; If the current standard deviation is less than the preset no-load air pressure fluctuation threshold, the current detection cycle is determined to be an invalid response state, and the flow resistance characteristic index is set to a preset value indicating no exhaust occurs.

7. The fully automatic vacuum continuous drying method for electrical coils according to claim 6, characterized in that, The flow resistance characteristic index is determined based on the heating power fluctuation and the cavity air pressure response, including: If the current standard deviation is greater than or equal to the preset no-load air pressure fluctuation threshold, the current detection cycle is determined to be in an effective response state. In the effective response state, a two-dimensional hysteresis trajectory is constructed based on the heating power fluctuation and the cavity air pressure response, with the heating power fluctuation as the horizontal axis and the cavity air pressure response as the vertical axis. The pressure response intensity is determined based on the regression slope of the two-dimensional hysteresis trajectory. The pressure response intensity is used to characterize the amplitude of external pressure fluctuations excited by unit heating power fluctuations. The pressure hysteresis is determined based on the closed area of ​​the two-dimensional hysteresis trajectory. The pressure hysteresis is used to characterize the time effect of gas being impeded inside the insulating layer. The flow resistance characteristic index is determined based on the pressure hysteresis and the pressure response intensity.

8. The fully automatic vacuum continuous drying method for electrical coils according to claim 2, characterized in that, Based on the flow resistance characteristic index, the rate of change of flow resistance characteristic is determined, including: The average of several flow resistance characteristic indices determined in the initial stage of drying will be used as a temporary benchmark value; If the temporary reference value is within a preset empirical safety range, the temporary reference value is determined as the initial flow resistance reference value; The deviation ratio of the real-time determined flow resistance characteristic index from the initial flow resistance reference value is determined as the flow resistance characteristic change rate.

9. The fully automatic vacuum continuous drying method for electrical coils according to claim 2, characterized in that, Controlling the increase of the base heating current includes: linearly increasing the base heating current using a preset fixed step size until the base heating current reaches a preset maximum allowable current; Controlling the decrease of the base heating current includes: using the value of the rate of change of the flow resistance characteristic as a penalty gain to exponentially decay the base heating current to obtain an adjusted current value. The larger the value of the rate of change of the flow resistance characteristic, the faster the rate of decrease of the base heating current. If the adjusted current value is less than the preset minimum sustaining current, the preset minimum sustaining current is determined as the basic heating current.

10. The fully automatic vacuum continuous drying method for electrical coils according to claim 5, characterized in that, The method further includes: Acquire the current air pressure data of the vacuum chamber, the standard deviation of the chamber air pressure response within the current detection period, and the current base heating current; If the current air pressure data is less than or equal to the process endpoint threshold, the standard deviation of the cavity air pressure response is less than the preset no-load air pressure fluctuation threshold, and the difference between the current basic heating current and the preset maximum allowable current is less than or equal to the preset current tolerance, then the drying process of the electrical coil is determined to be completed, and the basic heating current is cut off.

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