A thermostat output control system and method for an electrically heated humidifier

Abstract

The present application belongs to the technical field of electric heating humidification device control, and particularly relates to a constant temperature output control system and method for an electric heating humidifier; the method collects the temperature of a heating disc and the temperature of an air outlet in real time through a system, and predicts future temperature changes according to temperature change trends; through analysis of the temperature changes, the PWM weighting amount is dynamically adjusted, the heating power is accurately controlled, the temperature of humidified gas is kept stable, and in addition, the present application also introduces an overheating protection mechanism, uses a limited factor and an anti-accumulation coefficient to prevent power invalid accumulation of the heating disc in an overheating state, and avoids frequent triggering of the overheating protection mechanism; the technology can effectively improve energy utilization efficiency, shorten temperature recovery time, and ensure the comfort and safety of patients during treatment.

Description

Technical Field

[0001] This invention belongs to the field of electric heating humidification device control technology, specifically relating to a constant temperature output control system and method for an electric heating humidifier. Background Technology

[0002] Existing electric humidifiers are widely used in the medical and oxygen therapy fields, especially when providing humidified gas to patients undergoing oxygen therapy. These devices require stable, constant-temperature output to ensure patient comfort and safety during treatment. However, current technology has significant limitations in maintaining constant temperature output, particularly in key areas such as temperature control, scene switching, and recovery from loss of control. It fails to meet the requirements for high precision, dynamic adjustment, and real-time response. Specifically, this manifests in several ways: First, current humidifiers often rely on fixed temperature thresholds for detection and control. This involves using a preset temperature range and the gas cylinder outlet temperature to determine whether heating power needs adjustment. Since the temperature distribution of the heating plate in the gas pipeline is not uniform, especially when the ambient temperature is low, the outlet temperature often differs from the heating plate temperature by more than 5 degrees Celsius. Static detection methods struggle to accurately control the outlet gas temperature, leading to unnecessary waste of electricity. Second, during oxygen therapy, the patient's treatment needs... Changes may lead to a switch in the treatment environment. During environmental transitions, some patients' urgent need for oxygen may require hospitals to switch gas sources while maintaining airflow. This is especially true in northern regions when switching from room temperature to low-temperature gas sources. Existing temperature control systems may experience overheating lock-up under such extreme temperature differences. This occurs when the outlet temperature is lower than the target temperature, causing the system to increase its heating power, triggering the overheat protection of the heating plate. Although the overheating protection is brief, it can still affect patients. Furthermore, while the heating plate is under overheat protection, the outlet temperature may still not reach the target temperature, resulting in accumulated power adjustments. When the heating plate exits overheat protection, the accumulated power may be released, causing a momentary lock-up, which greatly impacts the patient's treatment outcome. Summary of the Invention

[0003] The purpose of this invention is to provide a constant temperature output control system and method for an electric heating humidifier, so as to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0004] To achieve the above objectives, a constant temperature output control system for an electric heating humidifier is provided, the system comprising:

[0005] The interactive module is started to complete the system startup initialization, scan and verify the key input, and output the running status to the display device.

[0006] The data acquisition and display module is used to acquire signals from the temperature sensor and the flow sensor, process the acquired signals to generate status values, and send the status values ​​and / or the display data generated therefrom to the display device.

[0007] The flow closed-loop module is used to obtain the actual flow of the fan, compare the actual flow with the target flow, and generate the fan speed control quantity;

[0008] The constant temperature control module is used to calculate and output the PWM duty cycle of the heating plate based on the state variables in order to adjust the heating power of the heating plate.

[0009] The monitoring and alarm module is used to monitor the status variables to identify anomalies, and after determining the fault priority of the anomalies, drive the audible and visual alarm device to sound an alarm and perform corresponding safety measures.

[0010] Furthermore, the acquisition and display module includes a data processing unit and a data conversion unit;

[0011] The data processing unit is used to perform digital filtering and averaging on the sampled signals from the temperature sensor and the flow sensor.

[0012] The data conversion unit is used to convert the processed sampled data into state variables for control calculations.

[0013] Furthermore, the acquisition and display module is also used to perform consistency verification on the display page of the display device, and to perform page correction when an abnormality is detected in the display page.

[0014] Furthermore, the flow closed-loop module is used to generate a fan speed control quantity based on the deviation between the target flow and the actual flow, and to feed the fan speed control quantity back to the fan.

[0015] Furthermore, the constant temperature control module includes a PWM adjustment unit, an over-temperature protection unit, and a waterless detection unit:

[0016] The over-temperature protection unit detects the heating plate temperature within a preset calculation cycle. When the heating plate temperature exceeds the preset upper limit temperature, or when the preset calculation cycle is reached and the heating plate temperature meets the preset drop trigger condition, it controls the heating plate to stop heating.

[0017] The PWM adjustment unit is used to predict the temperature of the tank outlet based on the temperature change trend when the temperature of the tank outlet is lower than the target temperature, and to calculate the PWM weighting amount and update the PWM duty cycle based on the change trend and prediction results.

[0018] The waterless detection unit is used to calculate the power-to-flow ratio and determine the water level in the tank during PWM updates and when the heating plate temperature meets the stable condition. It triggers an alarm when it determines that there is no water.

[0019] Furthermore, the following method is also run in the constant temperature control module:

[0020] S100: Initialize the target temperature, preset the calculation cycle, PWM duty cycle and PWM weighting, continuously collect the heating plate temperature, tank outlet temperature and actual flow rate and form status variables;

[0021] Furthermore, the system acquires the temperature of the heating plate and the temperature of the gas outlet of the tank through temperature sensors, and records the temperature of the heating plate as HT. i The temperature at the gas outlet of the tank is recorded as HJ. i The actual flow rate is obtained through the flow sensor and recorded as Qi, where i represents the data sequence number. All heating plate temperatures are arranged in the order of acquisition to form a sequence List1, all tank outlet temperatures are arranged in the order of acquisition to form a sequence List2, and all actual flow rates are arranged in the order of acquisition to form a sequence List3.

[0022] S200: Heating will stop when the temperature of the heating plate exceeds the preset upper limit temperature, or when the temperature of the tank outlet exceeds the target temperature after the preset calculation cycle is reached.

[0023] Furthermore, the temperature of the heating plate in the sequence List1 is detected in real time and the detection time is recorded. If the detection time is less than the preset calculation cycle time and the current heating plate temperature is detected to be greater than the preset upper limit temperature, the heating plate is controlled to stop heating.

[0024] When the detection time is less than the preset calculation cycle time, if the current heating plate temperature is detected to be higher than the target temperature, the absolute value of the difference between the current Ti tank outlet temperature and the previous Ti-1 tank outlet temperature is calculated as the change in the current Ti tank outlet temperature, denoted as ΔHJ. i The absolute value of the difference between the tank outlet temperature at the previous time Ti-1 and the tank outlet temperature at time Ti-2 is calculated as the change in tank outlet temperature ΔHJ at time Ti-1. i-1 If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is >1℃, control the gas outlet of the tank to stop heating. If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is ≤1℃, reduce the PWM weighting by ΔW.

[0025] S300: When the temperature at the tank outlet is lower than the target temperature, calculate the temperature change trend and predict the temperature at the tank outlet; if the trend is upward and the predicted temperature is higher than the target temperature, decrease the PWM weighting; otherwise, increase the PWM weighting; if the trend is downward, increase the PWM weighting, and calculate and update the PWM duty cycle based on the updated PWM weighting.

[0026] Furthermore, when the temperature at the outlet of the tank is lower than the target temperature, the change in temperature of the Ti heating plate at the current moment is calculated as ΔHJ. i The change in temperature of the heating plate at the next moment Ti+1 is ΔHJ. i+1 If △HJ i <△HJ i+1 Reduce the PWM weighting to ΔW;

[0027] When the temperature at the outlet of the tank is lower than the target temperature, the change in temperature of the Ti heating plate at the current moment is calculated as ΔHJ. i The change in temperature of the heating plate at the next moment Ti+1 is ΔHJ. i+1 If △HJ i >△HJ i+1 At that time, a predictive model is built to predict the temperature.

[0028] Furthermore, the method for predicting temperature by constructing a prediction model specifically includes:

[0029] In the sequence List2, for each historical data, the most recently collected p historical data are selected to construct the feature vector of the j-th data as φ(j);

[0030] Let j=1. Within the range of j, take 10s as the length of the detection window and calculate the average derivation S(j) of all historical data contained in the detection window according to the following formula.

[0031]

[0032] Where m represents the window length, m=10;

[0033] Set two empty sequences, H and C, respectively. Iterate through all the sizes of S(j). If S(j) ≥ 0, add the historical data and corresponding feature vector of the j-th window to sequence H. If S(j) < 0, add the historical data and corresponding feature vector of the j-th window to sequence C.

[0034] Set two empty sequences, H and C, respectively. Iterate through all the sizes of S(j). If S(j) ≥ 0, add the historical data and corresponding feature vector of the j-th window to sequence H. If S(j) < 0, add the historical data and corresponding feature vector of the j-th window to sequence C.

[0035] Two models are constructed based on sequence H and sequence C: and ,in and Given the least-squares closed-form solutions for sequences H and C respectively, calculate the trend offset g of the j-th historical data using the following method. j ;

[0036]

[0037] Where θ represents the tendency threshold, e is the natural constant, θ=0.0001, γ=100;

[0038] The prediction model is constructed based on the offset derivation and the trend offset as follows:

[0039]

[0040] in To predict the temperature data for the next time step, the model outputs... and g represents the transpose of the closed-form least-squares solution of sequences H and C. j This indicates the directional shift of the j-th historical data point. This represents the feature vector of the j-th data. If the temperature change of the predicted data is greater than the target temperature, the PWM weighting is reduced by ΔW; otherwise, the PWM weighting is increased by ΔW. The PWM is calculated based on the adjusted weights, and the calculation result is returned to the heating plate.

[0041] S400: During the PWM update process and when the heating plate temperature meets the stable condition, calculate the power-flow ratio and compare it with the preset threshold to determine the water volume status in the tank.

[0042] Furthermore, in S400, the power-to-flow ratio is the ratio between the output power of the heating plate and the gas flow rate at the outlet of the tank.

[0043] S500: When it is determined that there is no water, an audible and visual alarm is triggered and a safety procedure is performed, and then the process is repeated in a loop.

[0044] Furthermore, the following method is also run in the constant temperature control module:

[0045] S1: Generate a limiting factor based on the heating plate temperature and overheat protection status;

[0046] Furthermore, in step S1, the method for generating the limiting factor based on the heating plate temperature and the overheat protection status specifically includes:

[0047] In any given calculation cycle, the temperature HT of the heating plate is collected. i Simultaneously, the overheat protection stop heating flag Poff is read, the preset upper limit temperature is TlimT, and the upper limit temperature neighborhood width is δ. The plate temperature proximity is calculated using the following formula:

[0048]

[0049] Where sat(·) is the saturation function, and k represents the index of the calculation period;

[0050] in This represents the similarity of the heating plate temperature at time i in the k-th calculation cycle. K... T (k) Perform a bitwise AND operation with the result of the stop heating flag Poff, and record the result as K. s (k) is denoted as the restricted factor;

[0051] In step S2, the method of applying anti-cumulative constraints to the PWM weighting under the constrained state and smoothly releasing the anti-cumulative constraints after the constrained state is lifted specifically includes:

[0052] If the limiting factor is not zero, the heating plate is determined to be in a limited state. The anti-cumulative coefficient is calculated using the following expression: Kw(k) = e -（Ks（k）-1） -e+1;

[0053] Anti-cumulative constraints are applied to the PWM weighted quantity based on the anti-cumulative coefficient Kw(k), and the cumulative coefficient is multiplied by the adjustment weight to obtain the adjusted weight after constraint. S2: Anti-cumulative constraints are applied to the PWM weighted quantity under the constrained state, and the anti-cumulative constraints are smoothly released after the constrained state is lifted.

[0054] Furthermore, in step S2, the method of applying anti-cumulative constraints to the PWM weighting under the constrained state and smoothly releasing the anti-cumulative constraints after the constrained state is lifted specifically includes:

[0055] If the limiting factor is not zero, the heating plate is determined to be in a limited state. The anti-cumulative coefficient is calculated using the following expression: Kw(k) = e -（Ks（k）-1） -e+1;

[0056] Anti-cumulative constraints are applied to the PWM weighting based on the anti-cumulative coefficient Kw(k), and the cumulative coefficient is multiplied by the adjustment weight to obtain the adjusted weight after constraint.

[0057] Furthermore, the monitoring and alarm module includes a fault monitoring submodule, which includes the following fault monitoring units:

[0058] The breathing circuit status monitoring unit is used to monitor the connection status of the breathing circuit and generate abnormal fault indicators of the breathing circuit.

[0059] The oxygen concentration monitoring unit is used to monitor the oxygen concentration parameter and compare it with a preset threshold range to generate an oxygen concentration abnormality fault flag.

[0060] The shutdown alarm unit is used to detect the remaining oxygen content when the system is shut down and generate a shutdown abnormality fault indicator.

[0061] The tubing blockage monitoring unit is used to monitor the blockage status of the breathing tubing and generate a blockage fault indicator;

[0062] The flow deviation monitoring unit is used to monitor the deviation between the actual flow rate and the target flow rate and generate a flow deviation fault flag.

[0063] The detachment monitoring unit is used to monitor the detachment status of the nasal oxygen tube and generate a detachment fault indicator;

[0064] The power supply status monitoring unit is used to monitor the power supply status and generate a power outage fault flag.

[0065] The communication status monitoring unit is used to monitor the communication status of the oxygen sensor and generate communication abnormality fault flags;

[0066] The hierarchical alarm handling unit is used to receive all fault flags and perform fault priority determination, and output audible and visual alarms according to the priority.

[0067] Furthermore, the monitoring and alarm module also includes a readiness determination unit, which is used to determine the hardware readiness and output an audible and visual alarm if the hardware is not ready.

[0068] A method for controlling the constant temperature output of an electric humidifier, the method comprising the following steps:

[0069] A1, when the system starts, initializes control parameters such as target temperature, target flow rate, PWM duty cycle and PWM weighting, and cyclically scans the buttons to obtain user input parameters;

[0070] A2: Real-time acquisition of actual fan flow rate, and adjustment of actual flow rate based on user input parameters;

[0071] A3, the sensor collects signals and processes the data to generate status data for control and status data for display;

[0072] A4, Upload the display status data to the display device and correct the display result;

[0073] A5 monitors the collected status data for faults, prioritizes faults, and triggers audible and visual alarm devices to sound an alarm.

[0074] A6, PWM adjustment is performed based on the state data, and the heating plate is adjusted to maintain a constant temperature based on the adjustment result;

[0075] A7 performs a waterless detection when the temperature adjustment and temperature stability conditions are met, and triggers an alarm when there is no water.

[0076] Beneficial effects:

[0077] (I) Precise temperature control and energy efficiency optimization: This invention introduces a dynamically adjusted PWM weighting and a real-time temperature change prediction model. The model uses derived quantities and trend thresholds to help it quickly determine the trend of historical data changes. At the same time, the prediction results are more accurate when based on different reference models that are updated in real time. The system calculates the temperature change trend of the heating plate and the air outlet in real time, and dynamically adjusts the PWM weighting through the prediction model to achieve precise control of heating power, reduce temperature fluctuations and errors, and avoid unnecessary power waste.

[0078] (II) Intelligent control of overheat protection and power regulation: When the humidifier triggers overheat protection when the heating plate temperature is close to the upper limit, the system will intelligently control the PWM weighting amount by calculating the limiting factor and the anti-cumulative coefficient. In the overheat protection state, the anti-cumulative coefficient is 0, which prevents the accumulation of invalid PWM weighting amount when the heating plate stops heating and avoids excessive power increase. After heating is restored, the system smoothly releases the PWM weighting amount according to the anti-cumulative coefficient, which avoids the overheat protection being triggered again due to instantaneous power surge, significantly reduces the triggering frequency of overheat protection, shortens the temperature recovery time, ensures the stability of gas temperature during patient treatment, and improves patient comfort and treatment effect. Attached Figure Description

[0079] Figure 1 The diagram shown is a structural diagram of a constant temperature output control device for an electric heating humidifier.

[0080] Figure 2 The diagram shown is a flow chart of a constant temperature output control system for an electric humidifier.

[0081] Figure 3 The diagram shows the operation method flowchart of the constant temperature control module;

[0082] Figure 4 The diagram shown is a system structure diagram of the monitoring and alarm module.

[0083] Figure 5 The diagram shows a flow chart of a constant temperature output control method for an electric humidifier. Detailed Implementation

[0084] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0085] Please refer to Figure 1 As shown, the present invention provides a constant temperature output control device for an electric humidifier. The device includes a processor, a memory, a fan, a heating plate, a breathing tube temperature control device, a temperature sensor, a flow sensor, a key input device, a display device, and an audible and visual alarm device.

[0086] Please refer to Figure 2 As shown, the present invention also provides a constant temperature output control system for an electric humidifier, the system comprising the following five functional modules, the system being arranged in the processor of the device:

[0087] The interactive module is started to complete the system startup initialization, scan and verify the key input, and output the running status to the display device.

[0088] The data acquisition and display module is used to acquire signals from the temperature sensor and the flow sensor, process the acquired signals to generate status values, and send the status values ​​and / or the display data generated therefrom to the display device.

[0089] The flow closed-loop module is used to obtain the actual flow of the fan, compare the actual flow with the target flow, and generate the fan speed control quantity;

[0090] The constant temperature control module is used to calculate and output the PWM duty cycle of the heating plate based on the state variables in order to adjust the heating power of the heating plate.

[0091] The monitoring and alarm module is used to monitor the status variables to identify anomalies, and after determining the fault priority of the anomalies, drive the audible and visual alarm device to sound an alarm and perform corresponding safety measures.

[0092] Furthermore, the acquisition and display module includes a data processing unit and a data conversion unit;

[0093] The data processing unit is used to perform digital filtering and averaging on the sampled signals from the temperature sensor and the flow sensor.

[0094] The data processing unit first acquires real-time sampling signals from temperature and flow sensors. The temperature sensor monitors the temperature of the heating plate and the gas outlet of the tank, while the flow sensor monitors the actual airflow rate. Since the acquired signals may be affected by noise interference, the data processing unit first performs digital filtering on the raw sampling signals to eliminate high-frequency noise and smooth the signal. After filtering, the data processing unit performs averaging processing on the signals, such as using a moving average or sliding average method, to smooth the signal. By averaging data from multiple periods, errors caused by instantaneous changes are further reduced.

[0095] The data conversion unit is used to convert the processed sampled data into state variables for control calculations.

[0096] The data conversion unit receives signals from the temperature sensor and the flow sensor, and converts these signals into the state data required for control through a conversion algorithm. For example, for the temperature signal, the data conversion unit converts it into a temperature difference, that is, the difference between the current temperature and the target temperature; for the flow signal, the data conversion unit converts it into a flow deviation, that is, the deviation between the current flow and the target flow.

[0097] Furthermore, the acquisition and display module is also used to perform consistency verification on the display page of the display device, and to perform page correction when an abnormality is detected in the display page.

[0098] Specifically, the data acquisition and display module monitors in real time the match between the data displayed on the display device and the actual internal state of the system. If an inconsistency is detected between the displayed page and the actual data, such as an error in the temperature or flow rate display, the system will automatically perform a page correction operation. This operation includes reacquiring sensor data and updating the display content based on the latest acquired values.

[0099] Furthermore, the flow closed-loop module is used to generate a fan speed control quantity based on the deviation between the target flow and the actual flow, and to feed the fan speed control quantity back to the fan.

[0100] Specifically, the module receives the flow deviation generated by the data conversion unit. When the deviation between the actual flow and the target flow increases, the fan speed control quantity will increase accordingly, thereby increasing the fan speed. When the deviation decreases, the fan control quantity will decrease, so that the actual flow gradually approaches the expected target flow and maintains the stability of the flow.

[0101] Furthermore, the constant temperature control module includes a PWM adjustment unit, an over-temperature protection unit, and a waterless detection unit:

[0102] The over-temperature protection unit detects the heating plate temperature within a preset calculation cycle. When the heating plate temperature exceeds the preset upper limit temperature, or when the preset calculation cycle is reached and the heating plate temperature meets the preset drop trigger condition, it controls the heating plate to stop heating.

[0103] Specifically, the over-temperature protection unit is used to monitor the heating plate temperature and perform over-temperature protection. The system will monitor the heating plate temperature in real time during each preset calculation cycle; when the heating plate temperature is detected to exceed the preset upper limit temperature, the system will immediately trigger the over-temperature protection and control the heating plate to stop heating.

[0104] The PWM adjustment unit is used to predict the temperature of the tank outlet based on the temperature change trend when the temperature of the tank outlet is lower than the target temperature, and to calculate the PWM weighting amount and update the PWM duty cycle based on the change trend and prediction results.

[0105] Specifically, the PWM adjustment unit adjusts the heating power of the heating plate based on the deviation between the tank outlet temperature and the target temperature. When the tank outlet temperature is detected to be lower than the target temperature, the PWM adjustment unit predicts the tank outlet temperature based on the current temperature change trend. By analyzing the temperature change trend and the predicted temperature value, it calculates the updated PWM weighting and adjusts the PWM duty cycle to adjust the heating power to the target temperature.

[0106] The waterless detection unit is used to calculate the power-flow ratio and determine the water level in the tank during the PWM update process and when the heating plate temperature meets the stable condition. It triggers an alarm when it determines that there is no water.

[0107] Specifically, the waterless detection unit operates during the PWM update process of the system. When the temperature of the heating plate reaches a stable condition (e.g., the temperature change tends to be stable), the waterless detection unit starts to calculate the power-flow ratio and compares it with a preset threshold. Based on the comparison result, it determines whether there is water in the tank. If it is determined to be in a waterless state, the waterless detection unit will immediately trigger the audible and visual alarm device and issue an alarm signal to remind that the water level in the tank is insufficient.

[0108] Please refer to Figure 3 As shown, to explain the working process of the constant temperature control module in more detail, the present invention proposes the following method:

[0109] S100: Initializes the target temperature, preset calculation cycle, PWM duty cycle and PWM weighting, continuously collects the heating plate temperature, tank outlet temperature and actual flow rate and forms status variables.

[0110] After power is connected, the electric heater and fan are started. The controller initializes the control parameters related to constant temperature regulation. These control parameters include the target temperature, preset calculation period, PWM, and PWM weighting. The target temperature is the desired output temperature of the humidifier. The preset calculation period is used to limit the cycle of control calculation and parameter updates. PWM is the heating drive intensity of the heating plate (0 before startup). The PWM weighting is the adjustment weight W of the PWM adjustment amplitude under different operating conditions (initialized to 0). After initialization, the system obtains the heating plate temperature and the tank outlet temperature through temperature sensors, and records the heating plate temperature as HT. i The temperature at the gas outlet of the tank is recorded as HJ. i The actual flow rate is obtained by the flow sensor and recorded as Qi, where i represents the data sequence number. All heating plate temperatures are arranged in the order of acquisition to form a sequence List1, all tank outlet temperatures are arranged in the order of acquisition to form a sequence List2, and all actual flow rates are arranged in the order of acquisition to form a sequence List3.

[0111] S200: Heating will stop when the temperature of the heating plate exceeds the preset upper limit temperature, or when the temperature at the outlet of the tank exceeds the target temperature after the preset calculation cycle.

[0112] From the moment the system is powered on, the temperature of the heating plate in sequence List1 is monitored in real time and the monitoring duration is recorded. If the monitoring duration is less than the preset calculation cycle duration and the current heating plate temperature is detected to be greater than the preset upper limit temperature, the heating plate is controlled to stop heating. When the monitoring duration is less than the preset calculation cycle duration, if the current heating plate temperature is detected to be greater than the target temperature, the absolute value of the difference between the current Ti tank outlet temperature and the previous Ti-1 tank outlet temperature is calculated as the change in the current Ti tank outlet temperature, ΔHJ. i The absolute value of the difference between the tank outlet temperature at the previous time Ti-1 and the tank outlet temperature at time Ti-2 is calculated as the change in tank outlet temperature ΔHJ at time Ti-1. i-1 If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is >1℃, control the gas outlet of the tank to stop heating. If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is ≤1℃, reduce the PWM weighting by ΔW.

[0113] S300: When the temperature at the tank outlet is lower than the target temperature, calculate the temperature change trend and predict the temperature at the tank outlet; if the trend is upward and the predicted temperature is higher than the target temperature, decrease the PWM weighting; otherwise, increase the PWM weighting; if the trend is downward, increase the PWM weighting, and calculate and update the PWM duty cycle based on the updated PWM weighting.

[0114] Furthermore, when the temperature at the outlet of the tank is lower than the target temperature, the change in temperature of the Ti heating plate at the current moment is calculated as ΔHJ. i The change in temperature of the heating plate at the next moment Ti+1 is ΔHJ. i+1 If △HJ i <△HJ i+1 Reduce the PWM weighting to ΔW.

[0115] Furthermore, when the temperature at the outlet of the tank is lower than the target temperature, the change in temperature of the heating plate Ti at the current moment is calculated as ΔHJi, and the change in temperature of the heating plate Ti+1 at the next moment is calculated as ΔHJ. i+1 If △HJ i >△HJ i+1 At that time, temperature is predicted by constructing a predictive model;

[0116] Specifically, in sequence List2, all tank outlet temperatures are selected in reverse chronological order, starting from the most recently collected data point, and denoted as HJ as historical data. j , where j represents the sequence number of the historical data. For each historical data, the feature vector of the kth data is constructed by selecting the p most recently collected historical data.

[0117] Let j=1. Within the range of j, take 10s as the length of the detection window and calculate the average derivation S(j) of all historical data contained in the detection window according to the following formula.

[0118]

[0119] Where m represents the window length, m=10;

[0120] Set two empty sequences, H and C, respectively. Iterate through all the sizes of S(j). If S(j) ≥ 0, add the historical data and corresponding feature vector of the j-th window to sequence H. If S(j) < 0, add the historical data and corresponding feature vector of the j-th window to sequence C.

[0121] Two models are constructed based on sequence H and sequence C: and ,in and Given the least-squares closed-form solutions for sequences H and C respectively, calculate the trend offset g of the j-th historical data using the following method. j ;

[0122]

[0123] Where θ represents the tendency threshold, e is the natural constant, θ=0.0001, γ=100;

[0124] The prediction model is constructed based on the offset derivation and the trend offset as follows:

[0125]

[0126] in To predict the temperature data for the next time step, the model outputs... and g represents the transpose of the closed-form least-squares solution of sequences H and C. j This indicates the directional shift of the j-th historical data point. This represents the feature vector of the j-th data. If the temperature change of the predicted data is greater than the target temperature, the PWM weighting is reduced by ΔW; otherwise, the PWM weighting is increased by ΔW. The PWM is calculated based on the adjusted weights, and the calculation result is returned to the heating plate.

[0127] The trend shift calculated by the above method is based on the constant change in current historical data. The calculated trend shift determines whether a model built using sequence H or sequence C is used, rather than simply judging the trend shift based on temperature increases or decreases. This is because, during the acquisition period, the temperature data collected by the sensor is extremely prone to positive and negative jumps when calculating single-point temperature changes, and the magnitude of these changes is very small. Therefore, for the monitoring system, the heating operation status within a very short time range can be constantly disrupted. Furthermore, the heating effect of the heating plate is not immediately reflected in the sensor data; it requires propagation time. It is impossible to evaluate whether the temperature is rising or falling based on a single-point change. The above method calculates the average of changes over a specific length, reflecting the temperature change over a period of time, which precisely solves the problem of single-point changes determining the overall trend shift. The model addresses the issue of low-volume variation noise and misjudgment. It uses trend offset to determine parameter selection in the prediction model, rather than predicting based on changes within a specific historical period. In humidifier heating systems, overheat protection mechanisms exist. If the heating plate has triggered this mechanism, the data variation characteristics during the period from heating to resuming are inconsistent with the overall data, even though this data is factual. Therefore, even with data preprocessing algorithms, it's impossible to completely eliminate these inconsistencies. This prevents existing prediction methods from accurately determining the current data state and which historical data period should be used as a reference. The model introduced by sequence H and sequence C aims to solve the problem of existing prediction models failing to accurately select reference points, leading to erroneous judgments about the system state and achieving more accurate data prediction.

[0128] The temperature data for the next moment is predicted using a predictive model. The system calculates the temperature change of the predicted data. If the temperature change of the predicted data is greater than the target temperature, the PWM weighting is reduced by ΔW; otherwise, the PWM weighting is increased by ΔW. The PWM is then calculated based on the adjusted weights, and the calculation result is returned to the heating plate.

[0129] Meanwhile, during patient transport oxygen therapy, especially in northern winter environments when the gas source is switched from a normal temperature source to a cryogenic gas cylinder, the temperature of the gas entering the humidifier drops sharply, causing the outlet gas temperature to be significantly lower than the target temperature for a short period. The controller increases the heating plate output based on the outlet temperature error requirement, but the heating plate temperature is already close to the overheat protection limit. According to the protection requirements, heating plate heating must be stopped or limited, resulting in a limited ability to "increase the weighting of the heating plate to change the power when the outlet temperature is too low," thus prolonging the duration of the outlet temperature deviation.

[0130] To address the above problems, the present invention also provides the following solutions:

[0131] S1: Generate a limiting factor based on the heating plate temperature and overheat protection status.

[0132] Furthermore, in any given calculation cycle, the temperature HT of the heating plate is collected. i Simultaneously, the overheat protection stop heating flag Poff is read, the preset upper limit temperature is TlimT, and the upper limit temperature neighborhood width is δ. The plate temperature proximity is calculated using the following formula:

[0133]

[0134] Where sat(·) is the saturation function, and k represents the index of the calculation period;

[0135] in This represents the similarity of the heating plate temperature at time i in the k-th calculation cycle. K... T (k) Perform a bitwise AND operation with the result of the stop heating flag Poff, and record the result as K. s (k) is denoted as the restricted factor;

[0136] In step S2, the method of applying anti-cumulative constraints to the PWM weighting under the constrained state and smoothly releasing the anti-cumulative constraints after the constrained state is lifted specifically includes:

[0137] If the limiting factor is not zero, the heating plate is determined to be in a limited state. The anti-cumulative coefficient is calculated using the following expression: Kw(k) = e -（Ks（k）-1） -e+1;

[0138] The beneficial effects of the above steps are: sat() is used to limit the relationship between the heating plate temperature and the preset upper limit temperature, ensuring that the calculation result is between 0 and 1; the purpose of this formula is to calculate the plate temperature proximity, that is, the degree to which the heating plate temperature is close to the upper limit temperature, which is used to evaluate the possibility of the current heating plate overheating.

[0139] Perform an AND operation between KT(k) and the result of the heating stop flag Poff, and record the result as Ks(k), which is the constraint factor.

[0140] The limiting factor is used to evaluate the current heating state of the humidifier. When the limiting factor is non-zero, it indicates that the current humidifier is in an overheated state or close to an overheated state, that is, the humidifier is in a limited state.

[0141] S2: Apply anti-cumulative constraints to the PWM weighting under constrained conditions, and smoothly release the anti-cumulative constraints after the constrained conditions are lifted.

[0142] If the limiting factor is not zero, the heating plate is determined to be in a limited state. The anti-cumulative coefficient is calculated using the following expression: Kw(k) = e -（Ks（k）-1）-e+1, according to step S1, Ks(k) has only two results: 0 and 1. 0 means the system is unrestricted and the weight can be adjusted freely, while 1 means the system is restricted and the weight cannot be adjusted freely. Anti-cumulative constraint is applied to the PWM weight based on the anti-cumulative coefficient Kw(k). Specifically, the cumulative coefficient is multiplied by the adjustment weight as the adjustment weight after constraint.

[0143] When overheat protection is triggered, Poff(k) = 1, and Ks(k) must be 1. Therefore, the anti-cumulative coefficient Kw(k) must be 0 at this time. The calculated constrained adjustment weight is also zero, meaning no processing is performed on the adjustment weight, thus avoiding the accumulation of invalid weights during overheat protection. At the same time, when the system does not trigger overheat protection, Poff(k) = 0, and Ks(k) must be 0. The anti-cumulative coefficient Kw(k) must be 1 at this time. The calculated constrained adjustment weight is still retained, restoring the normal adjustment weight state of the system.

[0144] The beneficial effects of the above steps are as follows: when the overheat protection is triggered and the heating plate stops heating, the PWM weighted quantity will not accumulate invalidally during the output limitation period. When the plate temperature drops and heating can be resumed, the PWM weighted quantity is restored and updated in a smooth manner, thereby reducing the frequency of overheat protection being triggered again after recovery and shortening the duration of the output temperature deviating from the target.

[0145] S400: During the PWM update process and when the heating plate temperature meets the stable condition, calculate the power-to-flow ratio and compare it with the preset threshold to determine the water volume status in the tank.

[0146] During the PWM update process, if the temperature change of the heating plate meets the preset change threshold, the controller will calculate the power-to-flow ratio and compare it with the preset threshold. If the power-to-flow ratio is greater than or equal to the preset threshold, it is determined that there is water in the tank. If it is less than the preset threshold, it is determined that there is no water in the tank and an alarm signal is triggered.

[0147] Furthermore, the power-to-flow ratio is the ratio between the output power of the heating plate and the gas flow rate at the outlet of the tank.

[0148] S500: When it is determined that there is no water, an audible and visual alarm is triggered and a safety procedure is performed, and then the process returns to step S100 and repeats.

[0149] Please refer to Figure 4 As shown, the monitoring and alarm module includes a fault monitoring submodule, which includes the following fault monitoring units:

[0150] The breathing circuit status monitoring unit is used to monitor the connection status of the breathing circuit and generate abnormal fault indicators of the breathing circuit.

[0151] Specifically, the breathing circuit status monitoring unit monitors the changes in the bubble state in the circuit. If the bubble state changes abnormally large, it is determined that a leakage abnormality has occurred and an alarm is immediately triggered. The unit then immediately triggers an alarm and executes corrective measures until the alarm is deactivated. If the bubble state does not change abnormally large, it is determined that the trachea has not been inserted after power-on. Based on the determination result, a fault identifier is generated and transmitted to the graded alarm module through the fault monitoring system.

[0152] The oxygen concentration monitoring unit is used to monitor the oxygen concentration parameter and compare it with a preset threshold range to generate an oxygen concentration abnormality fault flag.

[0153] Specifically, the oxygen concentration monitoring unit is responsible for monitoring the oxygen concentration in real time and comparing it with a set threshold range. If the oxygen concentration exceeds the set threshold range, the system will generate an oxygen concentration abnormality fault flag and transmit it to the hierarchical alarm module through the fault monitoring system.

[0154] The shutdown alarm unit is used to detect the remaining oxygen content when the system is shut down and generate a shutdown abnormality fault indicator.

[0155] Specifically, when executing the shutdown command, if no oxygen concentration abnormality alarm is triggered, the shutdown alarm unit detects the remaining oxygen concentration in real time. If the remaining oxygen concentration is less than 33%, the shutdown command is executed; otherwise, a shutdown abnormality fault identifier is generated and transmitted to the hierarchical alarm module through the fault monitoring system.

[0156] The tubing blockage monitoring unit is used to monitor the blockage status of the breathing tubing and generate a blockage fault indicator;

[0157] Specifically, the tubing blockage monitoring unit is used to detect the blockage status of the breathing tubing, monitor whether the tubing is blocked in real time, and if a blockage is detected and the breathing circuit monitoring unit does not trigger an alarm, or if the alarm of the breathing circuit monitoring unit fails to be cleared, the tubing blockage monitoring unit determines that a blockage fault has occurred and immediately triggers an alarm, and performs processing measures after the alarm is triggered until the alarm is cleared.

[0158] The flow deviation monitoring unit is used to monitor the deviation between the actual flow rate and the target flow rate and generate a flow deviation fault flag.

[0159] Specifically, the flow deviation monitoring unit measures the deviation between the actual flow and the target flow, and makes a judgment based on time conditions. If the deviation between the actual flow and the target flow exceeds the preset tolerance range and continues to exceed the preset time threshold, a flow deviation fault flag is generated and transmitted to the hierarchical alarm module through the fault monitoring system.

[0160] The detachment monitoring unit is used to monitor the detachment status of the nasal oxygen tube and generate a detachment fault indicator;

[0161] Specifically, the detachment detection unit monitors the connection status of the nasal oxygen tube in real time and simultaneously detects the alarm status of the breathing circuit monitoring unit. If the breathing circuit monitoring unit does not alarm, the detachment detection unit determines that the nasal oxygen tube has detached and immediately alarms. If the alarm of the breathing circuit monitoring unit is not cleared, the alarm signal is cleared.

[0162] The power supply status monitoring unit is used to monitor the power supply status and generate a power outage fault flag.

[0163] Specifically, when the system cuts off the power supply, the power supply status monitoring unit first saves the existing data and exits. If the saved data is abnormal, it generates a power supply fault identifier after switching to the backup power supply and transmits it to the hierarchical alarm module through the fault monitoring system.

[0164] The communication status monitoring unit is used to monitor the communication status of the oxygen sensor and generate communication abnormality fault flags;

[0165] Specifically, the communication status monitoring unit establishes a communication connection between the oxygen sensor and the system monitoring unit, and monitors the communication response in real time. If a non-response or response timeout occurs, an alarm signal is immediately generated, and a response fault identifier is generated and marked as the highest priority.

[0166] The hierarchical alarm handling unit is used to receive all fault flags and perform fault priority determination, and output audible and visual alarms according to the priority.

[0167] Specifically, the hierarchical alarm handling unit receives various fault flags and performs priority determination to output corresponding audible and visual alarms. In practice, the fault priority determination module classifies faults into low, medium, and high levels, and outputs different alarm signals according to the priority. For low-level faults, a green indicator light is output and a buzzer emits an intermittent warning at a low frequency of 1 sound per second (approximately 70 dB); for medium-level faults, a yellow indicator light is output and a buzzer emits a continuous medium frequency sound at 2 sounds per second (approximately 85 dB); for high-level faults, a red indicator light is output and a buzzer emits a continuous high frequency sound at 4 sounds per second (approximately 100 dB), and the indicator light flashes 3 times per second.

[0168] Furthermore, the monitoring and alarm module also includes a readiness determination unit, which is used to determine the hardware readiness and output an audible and visual alarm if the hardware is not ready.

[0169] Please refer to Figure 5 As shown, the present invention also provides a method for controlling the constant temperature output of an electric humidifier, the method comprising the following steps:

[0170] A1, when the system starts, initializes control parameters such as target temperature, target flow rate, PWM duty cycle and PWM weighting, and cyclically scans the buttons to obtain user input parameters;

[0171] A2: Real-time acquisition of actual fan flow rate, and adjustment of actual flow rate based on user input parameters;

[0172] A3, the sensor collects signals and processes the data to generate status data for control and status data for display;

[0173] A4, Upload the display status data to the display device and correct the display result;

[0174] A5 monitors the collected status data for faults, prioritizes faults, and triggers audible and visual alarm devices to sound an alarm.

[0175] A6, PWM adjustment is performed based on the state data, and the heating plate is adjusted to maintain a constant temperature based on the adjustment result;

[0176] A7 performs a waterless detection when the temperature adjustment and temperature stability conditions are met, and triggers an alarm when there is no water.

[0177] Although the invention has been described in considerable detail and particularly with regard to several of the described embodiments, it is not intended to limit itself to any of these details or embodiments or any particular embodiment, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A constant temperature output control system for an electric humidifier, characterized in that, The system comprises the following five modules: The interactive module is started to complete the system startup initialization, scan and verify the key input, and output the running status to the display device. The data acquisition and display module is used to acquire signals from the temperature sensor and the flow sensor, process the acquired signals to generate status values, and send the status values ​​and / or the display data generated therefrom to the display device. The flow closed-loop module is used to obtain the actual flow of the fan, compare the actual flow with the target flow, and generate the fan speed control quantity; The constant temperature control module is used to calculate and output the PWM duty cycle of the heating plate based on the state variables in order to adjust the heating power of the heating plate. The monitoring and alarm module is used to monitor the status variables to identify anomalies, and after determining the fault priority of the anomalies, drive the audible and visual alarm device to sound an alarm and perform corresponding safety measures. The following method also runs in the temperature control module: S100: Initialize the target temperature, preset the calculation cycle, PWM duty cycle and PWM weighting, continuously collect the heating plate temperature, tank outlet temperature and actual flow rate and form status variables; S200: When the heating plate temperature exceeds the preset upper limit temperature, or when the tank outlet temperature exceeds the target temperature after the preset calculation cycle, heating will stop. S300: When the temperature at the tank outlet is lower than the target temperature, calculate the temperature change trend and predict the temperature at the tank outlet. If the trend is upward and the predicted temperature is greater than the target temperature, decrease the PWM weighting; otherwise, increase the PWM weighting. If the trend is downward, increase the PWM weighting and calculate and update the PWM duty cycle based on the updated PWM weighting. S400: During the PWM update process and when the heating plate temperature meets the stable condition, calculate the power-flow ratio and compare it with the preset threshold to determine the water volume status in the tank. S500: When it is determined that there is no water, an audible and visual alarm is triggered and a safety procedure is performed, and then the process is repeated in a loop. The method in step S300 specifically includes: when the temperature at the outlet of the tank is lower than the target temperature, calculating the change in the temperature of the Ti heating plate at the current moment as ΔHJ. i The change in temperature of the heating plate at the next moment Ti+1 is ΔHJ. i+1 If △HJ i <△HJ i+1 Reduce the PWM weighting to ΔW; When the temperature at the outlet of the tank is lower than the target temperature, the change in temperature of the Ti heating plate at the current moment is calculated as ΔHJ. i The change in temperature of the heating plate at the next moment Ti+1 is ΔHJ. i+1 If △HJ i >△HJ i+1 At that time, temperature is predicted by constructing a predictive model; The method for predicting temperature by constructing a prediction model specifically includes: In the sequence List2, for each historical data, the most recently collected p historical data are selected to construct the feature vector of the j-th data as φ(j); Let j=1. Within the range of j, take 10s as the length of the detection window and calculate the average derivation S(j) of all historical data contained in the detection window according to the following formula. Where m represents the window length, m=10; Set two empty sequences, H and C, respectively. Iterate through all the sizes of S(j). If S(j) ≥ 0, add the historical data and corresponding feature vector of the j-th window to sequence H. If S(j) < 0, add the historical data and corresponding feature vector of the j-th window to sequence C. Two models are constructed based on sequence H and sequence C: and ,in and Given the least-squares closed-form solutions for sequences H and C respectively, calculate the trend offset g of the j-th historical data using the following method. j ; Where θ represents the tendency threshold, e is the natural constant, θ=0.0001, γ=100; The prediction model is constructed based on the offset derivation and the trend offset as follows: in To predict the temperature data for the next time step, the model outputs... and g represents the transpose of the closed-form least-squares solution of sequences H and C. j This indicates the directional shift of the j-th historical data point. This represents the feature vector of the j-th data. If the temperature change of the predicted data is greater than the target temperature, the PWM weighting is reduced by ΔW; otherwise, the PWM weighting is increased by ΔW. The PWM is calculated based on the adjusted weights, and the calculation result is returned to the heating plate.

2. The constant temperature output control system for an electric humidifier according to claim 1, characterized in that, The acquisition and display module includes a data processing unit and a data conversion unit; The data processing unit is used to perform digital filtering and averaging on the sampled signals from the temperature sensor and the flow sensor. The data conversion unit is used to convert the processed sampled data into state variables for control calculations.

3. The constant temperature output control system for an electric humidifier according to claim 1, characterized in that, In S100, the system obtains the temperature of the heating plate and the temperature of the tank outlet through temperature sensors, and records the temperature of the heating plate as HT. i The temperature at the gas outlet of the tank is recorded as HJ. i The actual flow rate is obtained through the flow sensor and recorded as Qi, where i represents the data sequence number. All heating plate temperatures are arranged in the order of acquisition to form a sequence List1, all tank outlet temperatures are arranged in the order of acquisition to form a sequence List2, and all actual flow rates are arranged in the order of acquisition to form a sequence List3.

4. The constant temperature output control system for an electric humidifier according to claim 3, characterized in that, In S200, the temperature of the heating plate in the sequence List1 is detected in real time and the detection time is recorded. If the detection time is less than the preset calculation cycle time and the current heating plate temperature is detected to be greater than the preset upper limit temperature, the heating plate is controlled to stop heating. When the detection time is less than the preset calculation cycle time, if the current heating plate temperature is detected to be higher than the target temperature, the absolute value of the difference between the current Ti tank outlet temperature and the previous Ti-1 tank outlet temperature is calculated as the change in the current Ti tank outlet temperature, denoted as ΔHJ. i The absolute value of the difference between the tank outlet temperature at the previous time Ti-1 and the tank outlet temperature at time Ti-2 is calculated as the change in tank outlet temperature ΔHJ at time Ti-1. i-1 If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is >1℃, control the gas outlet of the tank to stop heating. If △HJ i >△HJ i-1 And △HJ i -△HJ i-1 When the temperature is ≤1℃, reduce the PWM weighting by ΔW.

5. The constant temperature output control system for an electric humidifier according to claim 1, characterized in that, The following method also runs in the temperature control module: S1: Generate a limiting factor based on the heating plate temperature and overheat protection status; S2: Apply anti-cumulative constraints to the PWM weighting under constrained conditions, and smoothly release the anti-cumulative constraints after the constrained conditions are lifted.

6. The constant temperature output control system for an electric humidifier according to claim 5, characterized in that, In step S1, the method for generating the limiting factor based on the heating plate temperature and the overheat protection status specifically includes: In any given calculation cycle, the temperature HT of the heating plate is collected. i Simultaneously, the overheat protection stop heating flag Poff is read, the preset upper limit temperature is TlimT, and the upper limit temperature neighborhood width is δ. The plate temperature proximity is calculated using the following formula: Where sat(·) is the saturation function, and k represents the index of the calculation period; Where K T (k) represents the temperature proximity of the heating plate at time i in the k-th calculation cycle. T (k) Perform a bitwise AND operation with the result of the stop heating flag Poff, and record the result as K. s (k) is denoted as the restricted factor; In step S2, the method of applying anti-cumulative constraints to the PWM weighting under the constrained state and smoothly releasing the anti-cumulative constraints after the constrained state is lifted specifically includes: If the limiting factor is not zero, the heating plate is determined to be in a limited state. The anti-cumulative coefficient is calculated using the following expression: Kw(k) = e -（Ks（k）-1） -e+1; Anti-cumulative constraints are applied to the PWM weighting based on the anti-cumulative coefficient Kw(k), and the cumulative coefficient is multiplied by the adjustment weight to obtain the adjusted weight after constraint.

7. A method for controlling the constant temperature output of an electric humidifier, wherein the method is applied to the constant temperature output control system of the electric humidifier according to any one of claims 1-6, characterized in that, The method includes the following steps: A1, when the system starts, initializes control parameters such as target temperature, target flow rate, PWM duty cycle and PWM weighting, and cyclically scans the buttons to obtain user input parameters; A2: Real-time acquisition of actual fan flow rate, and adjustment of actual flow rate based on user input parameters; A3, the sensor collects signals and processes the data to generate status data for control and status data for display; A4 will upload the status data to the display device and correct the display results. A5 monitors the collected status data for faults, prioritizes faults, and triggers audible and visual alarm devices to sound an alarm. A6 performs PWM adjustment based on the collected status data, and performs constant temperature coordination adjustment on the heating plate based on the adjustment result; A7 performs a waterless detection when the temperature adjustment and temperature stability conditions are met, and triggers an alarm when there is no water.

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