Control method and device of gas water heater and gas water heater

Abstract

The present application relates to the technical field of electrical equipment, and discloses a control method and device of a gas water heater and the gas water heater, the method comprising: collecting flue gas oxygen content data of a burner during combustion, pressure difference data of a gas passage outlet, surface temperature data of the burner and operation power data of the burner; determining an oxygen content deviation from a preset target oxygen content based on the flue gas oxygen content data, determining a load change trend based on the pressure difference data, calculating a load change rate based on the operation power data, calculating a temperature change rate based on the surface temperature data, and obtaining an air-fuel ratio deviation based on a preset fuzzy rule base through fuzzy reasoning; determining a feedforward compensation amount based on the load change trend; adjusting the air input amount of an air inlet passage into a premixing chamber and the gas amount of a gas passage into the premixing chamber based on the air-fuel ratio deviation and the feedforward compensation amount; and achieving uniform mixing of gas and air during the combustion process and improving the stability of the combustion state during the load switching process or under different working conditions.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment technology, specifically to a control method, device, and gas water heater for a gas water heater. Background Technology

[0002] In traditional fully premixed combustion control systems, most systems rely on a single oxygen sensor for feedback regulation. This makes it difficult to maintain an ideal metering ratio when the load fluctuates or the fuel composition changes. Furthermore, it can easily cause backfire or incomplete combustion during combustion, affecting the user experience. Summary of the Invention

[0003] This invention provides a control method, device, and gas water heater for gas water heaters, in order to solve the problems of difficulty in maintaining ideal metering ratio combustion when the load fluctuates or the fuel composition changes, and the easy occurrence of backfire or incomplete combustion during combustion.

[0004] In a first aspect, the present invention provides a control method for a gas water heater, the gas water heater comprising: a burner, an air inlet duct, a gas duct, and a premixing chamber, the premixing chamber being connected to the burner, the air inlet duct, and the gas duct, wherein the air in the air inlet duct and the gas in the gas duct are mixed in the premixing chamber and then delivered to the burner for combustion, the method comprising: Collect data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during the combustion process. The oxygen content deviation from the preset target oxygen content is determined based on flue gas oxygen content data; the load change trend is determined based on pressure difference data; the load change rate is calculated based on operating power data; and the temperature change rate is calculated based on surface temperature data. Based on a pre-set fuzzy rule base, fuzzy inference is performed on oxygen content deviation, load change rate and temperature change rate to obtain air-fuel ratio deviation; Determine the feedforward compensation amount based on the load change trend; The intake air volume of the premixed chamber in the intake air duct and the gas volume of the premixed chamber in the gas duct are adjusted based on the air-fuel ratio deviation and feedforward compensation.

[0005] This invention collects data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during combustion to determine oxygen content deviation, load change trend, and temperature change rate. Based on preset fuzzy rules, it performs fuzzy inference on each data point to obtain the air-fuel ratio deviation. Based on the load change trend, it determines the feedforward compensation amount. Furthermore, based on the air-fuel ratio deviation and the feedforward compensation amount, it determines the air intake of the premixing chamber and the gas input to the gas duct. This achieves adaptive air-fuel ratio adjustment, with coordinated feedforward and feedback control. Through a dynamic adjustment mechanism using fuzzy inference, it ensures combustion stability under different firepower levels. By introducing feedforward compensation to compensate for the adjustment amount, it improves the adjustment speed, enhances the stability of the combustion state during load switching, and maintains ideal metering ratio combustion under different load conditions or when fuel composition changes. This achieves uniform mixing of gas and air during combustion, thereby improving the system's adaptability and stability under complex operating conditions, solving the problems of backfire or incomplete combustion, and improving the user experience.

[0006] In one optional implementation, based on a preset fuzzy rule base, fuzzy inference is performed on the oxygen content deviation, load change rate, and temperature change rate to obtain the air-fuel ratio deviation, including: The oxygen content deviation, load change rate, and temperature change rate are mapped to fuzzy linguistic variables. Based on a pre-set fuzzy rule base, fuzzy reasoning is performed on the fuzzy linguistic variables corresponding to oxygen content deviation, load change rate, and temperature change rate to obtain the air-fuel ratio deviation.

[0007] This invention maps oxygen content deviation, load change rate, and temperature change rate into fuzzy linguistic variables and obtains the air-fuel ratio deviation through fuzzy inference based on a fuzzy rule base. This achieves unified fuzzy fusion of physical quantities in different dimensions, such as the trend of combustion state change, degree of combustion completeness, and heat exchange safety boundary. Thus, without relying on a precise mathematical model, it uses fuzzy inference rules to achieve rapid and smooth control of the air-fuel ratio deviation, and realizes strong anti-interference ability and dynamic adjustment ability of gas water heater combustion control when the load changes.

[0008] In one alternative implementation, determining the load change trend based on pressure difference data includes: Calculate the rate of change of pressure difference based on the pressure difference data, and determine the trend of the rate of change of pressure difference. When the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference, and the trend of change is increasing, the load change trend is determined to be increasing load. When the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference, and the trend of change is decreasing, the load change trend is determined to be a decrease in load.

[0009] This invention calculates the rate of change of pressure difference using pressure difference data and determines the trend of the rate of change of pressure difference. When the rate of change of pressure difference is greater than a preset threshold and shows a positive growth trend, it is determined that the load is increasing; otherwise, it is determined that the load is decreasing. This provides a basis for subsequent adjustment of fan speed and gas volume, and improves the reliability of adjustment.

[0010] In one optional embodiment, a gas proportional valve is provided at the gas outlet, and a fan is provided at the air inlet. The air intake volume of the premixing chamber and the gas volume of the premixing chamber are adjusted based on the air-fuel ratio deviation and feedforward compensation, including: Based on the air-fuel ratio deviation and feedforward compensation, determine the target valve opening adjustment of the gas proportional valve and the target speed adjustment of the fan. The valve opening of the gas proportional valve is adjusted based on the target valve opening adjustment amount, and the fan speed is adjusted based on the target speed adjustment amount.

[0011] This invention determines the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan by using air-fuel ratio deviation and feedforward compensation. The feedforward compensation amount predicts the load change trend in advance based on data such as pressure difference, and quickly provides the initial adjustment amount of the valve and fan, thereby significantly shortening the system response time and reducing water temperature fluctuations. At the same time, the feedback adjustment based on air-fuel ratio deviation can maintain the correction amount to avoid errors caused by fluctuations in gas calorific value and environmental changes. The fusion of air-fuel ratio deviation and feedforward compensation amount can improve the system response speed and achieve stable combustion in the gas water heater.

[0012] In one optional implementation, the feedforward compensation amount includes a first valve opening adjustment amount and a first speed adjustment amount. Based on the air-fuel ratio deviation and the feedforward compensation amount, the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan are determined, including: Based on the air-fuel ratio deviation, determine the adjustment amount of the second valve opening and the adjustment amount of the second speed. Based on the sum of the first valve opening adjustment amount and the second valve opening adjustment amount, the target valve opening adjustment amount is determined, and based on the sum of the first speed adjustment amount and the second speed adjustment amount, the target speed adjustment amount is determined. When the load change trend is that the load is increasing, the target valve opening adjustment amount is used to increase the valve opening and the target speed adjustment amount is used to increase the fan speed. When the load change trend is that the load is decreasing, the target valve opening adjustment amount is used to decrease the valve opening and the target speed adjustment amount is used to decrease the fan speed.

[0013] This invention uses a first adjustment amount to predict sudden load changes and quickly make coarse adjustments to valves and fans. It then uses a second adjustment amount for precise adjustment, combining the sum of the first and second valve opening adjustment amounts and the sum of the first and second speed adjustment amounts. When the load increases, the gas and air are increased simultaneously, and when the load decreases, the gas and air are decreased simultaneously, thus maintaining the optimal air-fuel ratio and achieving constant temperature and efficient combustion under all operating conditions.

[0014] In one alternative implementation, the method further includes: During the operation of the gas water heater, in response to the detection that the heat output power of the gas water heater is less than the preset heat output power threshold, the current speed of the fan is maintained, and the gas injection frequency of the gas proportional valve is adjusted based on the current surface temperature of the burner.

[0015] This invention adjusts the proportional injection frequency of the gas valve to regulate the gas supply per unit time and improve the mixing effect of gas and air when the heat output power of the gas water heater is less than a preset heat output power threshold, thereby achieving the expected heat output power.

[0016] In one alternative implementation, adjusting the gas injection frequency of the gas proportional valve based on the current surface temperature of the burner includes: In response to the current surface temperature being greater than a first temperature threshold, the gas injection frequency of the gas proportional valve is reduced. In response to the current surface temperature being lower than the second temperature threshold, the gas injection frequency of the gas proportional valve is increased, where the second temperature threshold is lower than the first temperature threshold.

[0017] This invention detects the current surface temperature of the burner and adjusts the gas injection frequency based on the relationship between the current surface temperature and different temperature thresholds. This achieves precise control of the injection quantity at different temperatures, improves combustion stability, and ensures the safety of the water heater, thus moving from passive protection to active defense.

[0018] In one alternative implementation, the method further includes: During the operation of a gas water heater, in response to the detection that the rate of change of the burner surface temperature exceeds the preset temperature change rate threshold, the fan speed is increased, the gas injection frequency of the gas proportional valve is reduced, or the gas proportional valve is controlled to stop injecting gas.

[0019] This invention increases the fan speed when the rate of change of the burner surface temperature exceeds a preset temperature change rate threshold, thereby preventing backfire while ensuring the safe use of the gas water heater.

[0020] Secondly, the present invention provides a control device for a gas water heater. The gas water heater includes: a burner, an air inlet duct, a gas duct, and a premixing chamber. The premixing chamber is connected to the burner, the air inlet duct, and the gas duct. The air in the air inlet duct and the gas in the gas duct are mixed in the premixing chamber and then delivered to the burner for combustion. The device includes: The data acquisition module is used to collect data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during the combustion process. The first determining module is used to determine the oxygen content deviation from the preset target oxygen content based on flue gas oxygen content data, determine the load change trend based on pressure difference data, calculate the load change rate based on operating power data, and calculate the temperature change rate based on surface temperature data. The reasoning module is used to perform fuzzy reasoning on oxygen content deviation, load change rate and temperature change rate based on a preset fuzzy rule base to obtain air-fuel ratio deviation. The second determining module is used to determine the feedforward compensation amount based on the load change trend; The adjustment module is used to adjust the air intake volume of the premixed chamber in the air intake duct and the gas volume of the premixed chamber in the gas duct based on the air-fuel ratio deviation and feedforward compensation.

[0021] Thirdly, the present invention provides a gas water heater, comprising: a burner, an air inlet duct, a gas duct, and a premixing chamber. The premixing chamber is connected to the burner, the air inlet duct, and the gas duct. The air in the air inlet duct and the gas in the gas duct are mixed in the premixing chamber and then delivered to the burner for combustion. The burner further comprises a controller, which includes: The memory and the processor are interconnected and communicate with each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the method described in the first aspect or any of its corresponding embodiments.

[0022] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the method described in the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of an application scenario according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a first method for controlling a gas water heater according to an embodiment of the present invention; Figure 3 This is a second flowchart illustrating the control method for a gas water heater according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the system framework of a gas water heater according to an embodiment of the present invention; Figure 5 This is a structural block diagram of the control device for a gas water heater according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the hardware structure of the controller according to an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0026] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Figure 1 This is a schematic diagram of an optional application scenario of an embodiment of the present invention, such as... Figure 1 As shown, a gas water heater includes: a burner 101, an air inlet duct 103, a gas passage 104, and a premixing chamber 102. The premixing chamber 102 is connected to the burner 101, the air inlet duct 103, and the gas passage 104. The air from the air inlet duct 103 and the gas from the gas passage 104 are mixed in the premixing chamber and then delivered to the burner 101 for combustion. The burner 101 also includes a controller. Figure 1 (Not shown in the text) The controller is used to execute the control method of the gas water heater. The overall process of the controller executing the control method of the gas water heater is detailed in the relevant description of the method embodiment below, and will not be repeated here.

[0029] Traditional fully premixed combustion control systems suffer from insufficient air-fuel ratio control precision. Most systems rely solely on a single oxygen sensor for feedback adjustment, lacking comprehensive sensing capabilities for multiple parameters such as gas flow rate, intake air pressure, and environmental changes. This makes it difficult to maintain ideal metering ratio combustion when load fluctuates or fuel composition changes. Secondly, the system response is sluggish, with poor dynamic performance, failing to predict sudden changes in flow rate trends in advance, resulting in unstable combustion during load switching and even the risk of flameout or deflagration. Furthermore, under extremely low load conditions, limited fan speed regulation and insufficient air supply lead to uneven gas mixing, causing backfire or incomplete combustion.

[0030] In related technologies, there is a general lack of active safety protection mechanisms. Dangerous conditions such as backfire and flameout are mostly dealt with by post-event alarms or gas supply cutoff, failing to achieve pre-event prediction and intervention. The perception of the burner is limited, the control strategy is static, the feedforward and feedback are disconnected, and the safety control is passive.

[0031] This invention, through in-depth analysis of operational data from multiple fully premixed combustion devices, gradually identifies the root causes of system performance bottlenecks. During load switching transients, flue gas oxygen content fluctuations can reach ±3%, far exceeding the steady-state control accuracy requirements; emissions of nitric oxide and nitrogen dioxide abnormally increase during low-load operation, which is found to be caused by localized oxygen-deficient combustion; prior to multiple backfire incidents, burner surface temperatures had been continuously rising, but the system failed to issue warnings; and combustion efficiency varied significantly across different regions for the same equipment due to differences in atmospheric pressure and humidity. The traditional "single-point feedback + static control" architecture can no longer meet the demands of high-performance combustion control, necessitating the construction of a dynamic closed-loop control system that integrates multi-source sensing, supports feedforward prediction, and active protection. By systematically reviewing control theory, sensor fusion algorithms, and combustion dynamics models, a control method for gas water heaters is ultimately proposed, based on multi-sensor fusion, with a dynamic air-fuel ratio adaptive model as the core, feedforward and feedback coordinated control as the means, and active safety suppression as the guarantee.

[0032] According to an embodiment of the present invention, a control method for a gas water heater is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0033] This embodiment provides a control method for a gas water heater, which can be used in the controller of the aforementioned gas water heater. Figure 2 This is a schematic flowchart of a first method for controlling a gas water heater according to an embodiment of the present invention, as shown below. Figure 2 As shown, the process includes the following steps: Step S201: Collect data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during the combustion process.

[0034] It should be noted that the flue gas oxygen content data is obtained through a flue gas oxygen content sensor; the pressure difference data at the gas duct outlet is obtained through a gas duct outlet pressure sensor; the surface temperature data of the burner is obtained through a burner surface temperature sensor; and the operating power data of the burner during combustion is collected in real time.

[0035] Among them, flue gas oxygen content data is used to provide feedback on whether the air-fuel ratio is close to the ideal stoichiometric ratio, gas outlet pressure difference data is used to determine the trend of gas and air flow changes, and burner surface temperature data is used to identify whether the burner is in the flashback risk zone.

[0036] Among them, flue gas oxygen content refers to the volume percentage of residual oxygen in the exhaust gas, which is used to reflect whether the mixing ratio of air and gas is reasonable. Too high flue gas oxygen content indicates high wind speed or insufficient gas, i.e., low thermal efficiency; too low flue gas oxygen content indicates incomplete combustion, which easily produces carbon monoxide.

[0037] The pressure difference at the gas outlet reflects the gas injection velocity, thereby controlling the amount of gas entering the burner. Burner surface temperature data reflects the combustion state and heat load, and is also used to protect the machine from dry burning or backfire; the operating power during burner operation refers to the heat output power of the gas water heater.

[0038] In some optional implementations of this embodiment, the working process of the gas water heater can be that the user sets the water temperature, the gas water heater changes its operating power based on the water temperature, controls the gas outlet pressure difference to change the gas volume, and coordinates with the fan to adjust the oxygen content of the flue gas to a reasonable range, and the burner surface temperature is stabilized at the corresponding value.

[0039] Step S202: Determine the oxygen content deviation from the preset target oxygen content based on flue gas oxygen content data, determine the load change trend based on pressure difference data, calculate the load change rate based on operating power data, and calculate the temperature change rate based on surface temperature data.

[0040] It should be noted that the preset target oxygen content can be the target oxygen content that enables the gas to burn completely.

[0041] The pressure difference at the gas outlet reflects load changes because of the matching relationship between the fan speed and the gas valve opening. The pressure difference is related to the state of combustion. By setting a pressure difference parameter value corresponding to the target load and comparing it in real time, the direction of pressure difference deviation can be determined, thus allowing for early or synchronous detection of load increases or decreases. Calculating the temperature change rate based on surface temperature data can identify overheating, backfire, and other conditions.

[0042] The load change rate is calculated from the operating power data. It can be calculated as the ratio of the change in operating power to the time required for the change. For example, when the operating power of the burner is adjusted from the current value to 110 of its rated power within 1 minute, the load change rate is 10% / min.

[0043] Step S203: Based on the preset fuzzy rule base, fuzzy reasoning is performed on the oxygen content deviation, load change rate and temperature change rate to obtain the air-fuel ratio deviation.

[0044] The dynamic air-fuel ratio of a gas water heater refers to a dynamic value in which the control system automatically adjusts the mixing ratio of gas flow and air flow (or wind pressure) based on real-time detection during the operation of the water heater, so that it always maintains the optimal combustion state.

[0045] It should be noted that, in order to improve the accuracy and stability of the data, the system uses adaptive filtering technology to process the collected oxygen content deviation, load change rate, and temperature change rate; by using algorithms such as Kalman filtering or wavelet transform, sensor noise interference is effectively eliminated, the signal-to-noise ratio of the input data is improved, thereby enhancing the accuracy of the feedforward compensation mechanism.

[0046] Based on the pre-processed oxygen content deviation, load change rate, and temperature change rate, the system constructs a DAFRAM model. This model introduces a fuzzy logic control mechanism, which performs fuzzy processing on the input oxygen content deviation, load change rate, and temperature change rate through a preset fuzzy rule base, and dynamically calculates the current optimal air-fuel ratio through a fuzzy inference mechanism, outputting an air-fuel ratio deviation signal.

[0047] Step S204: Determine the feedforward compensation amount based on the load change trend.

[0048] It should be noted that the fan speed determines the air intake volume of the air intake duct, and the opening degree of the gas valve determines the gas volume; changes in load can reflect deviations in the air-fuel ratio, which are caused by fluctuations in the pressure difference. Therefore, the required feedforward compensation amount can be determined by the load change trend.

[0049] For example, if it is determined that the load is about to increase, the fan speed needs to be increased to increase the airflow or the gas valve opening needs to be reduced; if it is determined that the load is about to decrease, the fan speed needs to be reduced, etc.

[0050] Specifically, a feedforward compensation mechanism is introduced, which uses the gas outlet pressure sensor to predict the load change trend and adjusts the fan speed and gas proportional valve opening in advance before the user changes the settings, so as to achieve "adjust before combustion" and significantly shorten the response time.

[0051] Step S205: Adjust the air intake volume of the air intake duct into the premixing chamber and the gas volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and feedforward compensation amount.

[0052] It should be noted that the adjustment speed is improved by integrating the air-fuel ratio deviation with the feedforward compensation. For example, when the oxygen content is low and the proportion of fuel gas is high, increasing the wind speed can theoretically increase the oxygen content, but the adjustment speed is slow. Therefore, a feedforward compensation is introduced to compensate for the adjustment amount and improve the adjustment speed.

[0053] The control method for a gas water heater provided in this embodiment collects data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during combustion. This data determines the oxygen content deviation, load change trend, and temperature change rate. Based on preset fuzzy rules, fuzzy inference is performed on each data point to obtain the air-fuel ratio deviation. The feedforward compensation amount is determined based on the load change trend. Furthermore, the air intake of the premixing chamber and the gas input through the gas duct are determined based on the air-fuel ratio deviation and the feedforward compensation amount. This achieves adaptive air-fuel ratio adjustment and coordinated feedforward and feedback control. Through a dynamic adjustment mechanism based on fuzzy inference, combustion stability under different heat levels is ensured. The introduction of feedforward compensation improves the adjustment speed, enhances the stability of the combustion state during load switching, and maintains ideal metering ratio combustion under different load conditions or when fuel composition changes. This achieves uniform mixing of gas and air during combustion, thereby improving the system's adaptability and stability under complex operating conditions, solving the problems of backfire or incomplete combustion, and improving the user experience.

[0054] This embodiment provides a control method for a gas water heater, which can be used in the controller of the aforementioned gas water heater. Figure 3 This is a schematic diagram of a second process for controlling a gas water heater according to an embodiment of the present invention, as shown below. Figure 3 As shown, the process includes the following steps: Step S301: Collect data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and operating power during the combustion process. For details, please refer to [link to relevant documentation]. Figure 2 Step S201 of the illustrated embodiment will not be described again here.

[0055] Step S302: Determine the oxygen content deviation from the preset target oxygen content based on flue gas oxygen content data, determine the load change trend based on pressure difference data, calculate the load change rate based on operating power data, and calculate the temperature change rate based on surface temperature data.

[0056] Specifically, step S302 includes: Step S3021: Calculate the rate of change of pressure difference based on the pressure difference data, and determine the trend of the rate of change of pressure difference.

[0057] It should be noted that the system acquires the pressure difference data at the outlet of the gas proportional valve in real time at high frequency. After eliminating sensor noise using a Kalman filter algorithm, it calculates the instantaneous slope of the pressure difference over time to determine the rate of change of the pressure difference. This instantaneous slope can be used as a priori signal for load abrupt changes.

[0058] Step S3022: When the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference and the trend of change is increasing, the load change trend is determined to be increasing load.

[0059] The pressure change rate reflects the speed of load change. A preset threshold, set based on experimental data, distinguishes between normal and abnormal fluctuations. Only when the pressure difference change rate exceeds the preset threshold is a trend considered, reducing false positives and avoiding unnecessary adjustments.

[0060] When the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference and shows a positive growth trend, the system can determine that the user is about to turn on or reduce the water flow based on the fact that the flow rate is proportional to the square root of the pressure difference, thereby determining that the load change trend is an increase in load.

[0061] Step S3023: When the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference and the trend of change is decreasing, the load change trend is determined to be decreasing.

[0062] The decreasing trend refers to a negative growth trend in the pressure difference change rate. When the pressure difference change rate is greater than the preset pressure difference change rate threshold and shows a negative growth trend, it is determined to be a sudden load reduction, thus confirming the load change trend as a decrease in load. First, it is determined whether the pressure difference change rate exceeds the preset pressure difference change rate threshold. Only when the pressure difference change rate exceeds the preset pressure difference change rate threshold is the trend of the pressure difference change rate further analyzed to avoid misjudgments due to minor fluctuations and reduce unnecessary adjustments.

[0063] The control method for gas water heaters provided in this embodiment calculates the rate of change of pressure difference using pressure difference data and determines the trend of the rate of change of pressure difference. When the rate of change of pressure difference is greater than the preset threshold and shows a positive growth trend, it is determined that the load is increasing; otherwise, it is determined that the load is decreasing. This provides a basis for subsequent adjustment of fan speed and gas volume, thereby improving the reliability of adjustment.

[0064] Step S303: Based on the preset fuzzy rule base, perform fuzzy reasoning on the oxygen content deviation, load change rate and temperature change rate to obtain the air-fuel ratio deviation.

[0065] Specifically, step S303 includes: Step S3031: Map oxygen content deviation, load change rate, and temperature change rate into fuzzy linguistic variables.

[0066] It should be noted that the oxygen content deviation, load change rate, and temperature change rate are numerical values ​​before fuzzy processing. After mapping these values ​​to fuzzy linguistic variables, they become corresponding linguistic variables. These linguistic variables describe the magnitude of the deviation corresponding to these values, such as too high or too high. For example, there is almost no difference between an oxygen content deviation of "+1.5% and +1.6%", and it is very likely that it is a normal small fluctuation or a small error in sensor acquisition. Therefore, after mapping to fuzzy linguistic variables, deviations of +1.5% and +1.6% can belong to the same deviation range. That is, the oxygen content deviation will not be repeatedly adjusted within a certain range, making the control smoother. The mapping of the load change rate and temperature change rate is the same as the mapping of the oxygen content in the example above.

[0067] Step S3032: Based on the preset fuzzy rule base, perform fuzzy reasoning on the fuzzy linguistic variables corresponding to oxygen content deviation, load change rate and temperature change rate to obtain air-fuel ratio deviation.

[0068] Among them, fuzzy reasoning is performed through a preset expert rule base. This rule base introduces the load change trend as a pre-judgment condition, thereby predicting the direction of air-fuel ratio deviation and outputting the basic correction amount before the combustion state deteriorates.

[0069] For example, the preset expert rule base can have different adjustment conditions, and the adjustment amount is different under different fuzzy languages. For instance, if the oxygen content deviation obtained by mapping to fuzzy language is large, it means that the oxygen content is low and the oxygen content needs to be increased accordingly.

[0070] The adjustment logic for the load change rate can be as follows: if the load change rate, when mapped to fuzzy language, shows a positive increase (i.e., a sharp increase), it indicates that the combustion load is rising rapidly, requiring a corresponding rapid increase in the amount of fuel gas and air intake to maintain the air-fuel ratio and increase power; conversely, if the load change rate, when mapped to fuzzy language, shows a negative increase, it indicates that the combustion load is falling rapidly, requiring a corresponding rapid decrease in the amount of fuel gas and air intake to maintain the air-fuel ratio and reduce power.

[0071] The adjustment logic for the temperature change rate can be as follows: when the temperature change rate, mapped to fuzzy language, shows a positive increase, it indicates that the burner surface is overheating, which may be due to insufficient water flow or dry burning, requiring a significant reduction in the gas supply or even shutting off the gas supply. Thus, fuzzy logic reasoning is used to inversely assess the deviation between the current actual air-fuel ratio and the target air-fuel ratio.

[0072] The control method for gas water heaters provided in this embodiment maps oxygen content deviation, load change rate, and temperature change rate into fuzzy linguistic variables and obtains air-fuel ratio deviation through fuzzy inference based on a fuzzy rule base. This achieves unified fuzzy fusion of physical quantities in different dimensions, such as combustion state change trends, combustion completeness, and heat exchange safety boundaries. Thus, without relying on a precise mathematical model, it achieves rapid and smooth control of air-fuel ratio deviation using fuzzy inference rules, realizing strong anti-interference capability and dynamic adjustment capability of gas water heater combustion control when the load changes.

[0073] Step S304: Determine the feedforward compensation amount based on the load change trend. For details, please refer to [link to relevant documentation]. Figure 2 Step S204 of the illustrated embodiment will not be described again here.

[0074] Step S305: Adjust the air intake volume of the air intake duct into the premixing chamber and the gas volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and feedforward compensation amount.

[0075] A gas proportional valve is installed at the gas outlet, and a fan is installed at the air inlet.

[0076] Specifically, step S305 includes: Step S3051: Based on the air-fuel ratio deviation and feedforward compensation, determine the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan.

[0077] Specifically, the gas delivery volume is adjusted by regulating the target valve opening of the gas proportional valve, and the air intake volume, i.e., the air circulation volume, is adjusted by regulating the target rotation speed.

[0078] The feedforward compensation includes the first valve opening adjustment and the first speed adjustment.

[0079] In some optional implementations, step S3051 above includes: Step a1: Based on the air-fuel ratio deviation, determine the adjustment amount of the second valve opening and the adjustment amount of the second speed.

[0080] It should be noted that the second valve opening adjustment amount is how much the gas proportional valve needs to be opened or closed further from its current position; the second speed adjustment amount is how much the fan needs to be increased or decreased from its current speed.

[0081] Step a2: Based on the sum of the first valve opening adjustment amount and the second valve opening adjustment amount, determine the target valve opening adjustment amount, and based on the sum of the first speed adjustment amount and the second speed adjustment amount, determine the target speed adjustment amount; when the load change trend is that the load is increasing, the target valve opening adjustment amount is used to increase the valve opening, and the target speed adjustment amount is used to increase the fan speed; when the load change trend is that the load is decreasing, the target valve opening adjustment amount is used to decrease the valve opening, and the target speed adjustment amount is used to decrease the fan speed.

[0082] For example, when a surge in load is predicted but the current oxygen content is already high (risk of oxygen deficiency), the fuzzy rule will prioritize limiting the increase in gas opening and instead force a significant increase in fan speed to ensure that the air-fuel mixture ratio does not deviate from the safe range. This achieves gas-air synchronization within milliseconds, solving the risk of cold water shock or overheating caused by water temperature lag in traditional control.

[0083] The control method for the gas water heater provided in this embodiment predicts sudden load changes through a first adjustment amount, quickly and coarsely adjusts the valves and fan, and makes precise adjustments through a second adjustment amount. It integrates the sum of the first valve opening adjustment amount and the second valve opening adjustment amount, as well as the sum of the first speed adjustment amount and the second speed adjustment amount. When the load increases, the gas and air are increased simultaneously, and when the load decreases, the gas and air are decreased simultaneously, always maintaining the optimal air-fuel ratio and achieving constant temperature and efficient combustion under all operating conditions.

[0084] Step S3052: Adjust the valve opening of the gas proportional valve based on the target valve opening adjustment amount, and adjust the fan speed based on the target speed adjustment amount.

[0085] It should be noted that the gas proportional valve increases or decreases the valve opening according to the target opening amount to change the gas flow, while the fan increases or decreases the speed according to the target speed to change the air volume, so that the air-fuel ratio and combustion load can be accurately achieved to the expected state.

[0086] The control method for a gas water heater provided in this embodiment determines the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan by using air-fuel ratio deviation and feedforward compensation amount. The feedforward compensation amount predicts the load change trend in advance based on data such as pressure difference and quickly provides the initial adjustment amount of valve and fan, thereby significantly shortening the system response time and reducing water temperature fluctuations. At the same time, the feedback adjustment based on air-fuel ratio deviation can maintain the error caused by fluctuations in gas calorific value and environmental changes. The fusion of air-fuel ratio deviation and feedforward compensation amount can improve the system response speed and achieve stable combustion of the gas water heater.

[0087] Step S306: During the operation of the gas water heater, in response to the detection that the heat output power of the gas water heater is less than the preset heat output power threshold, the current speed of the fan is maintained, and the gas injection frequency of the gas proportional valve is adjusted based on the current surface temperature of the burner.

[0088] It should be noted that if the heat output power of a gas water heater is less than the preset heat output power threshold, it may indicate insufficient gas supply, excessive or insufficient air intake leading to low burner efficiency, or excessive water flow in the heat exchanger causing excessive heat loss. In such cases, adjusting the gas injection frequency of the gas proportional valve helps regulate the gas supply per unit time and improve the mixing effect of gas and air, thereby achieving the expected heat output power. This can be achieved using the heat balance formula Q=Cp×ρ×Qwater×(Tset) Tin) calculates the thermal output power; where the preset thermal output power threshold is the rated power.

[0089] The preset heat output power is related to factors such as combustion temperature and combustion state. The preset heat output power is used to characterize the power required for the burner to maintain normal combustion. The preset heat output power can be between 20% and 30%, and for example, it can be 20%.

[0090] The control method for a gas water heater provided in this embodiment adjusts the proportional injection frequency of the gas valve to regulate the gas supply per unit time and improve the mixing effect of gas and air when the heat output power of the gas water heater is less than a preset heat output power threshold, thereby achieving the expected heat output power.

[0091] Specifically, step S306 includes: Step b1: In response to the current surface temperature being greater than a first temperature threshold, reduce the gas injection frequency of the gas proportional valve; the first temperature threshold is used to characterize the maximum allowable temperature during normal combustion of the burner.

[0092] It should be noted that reducing the gas injection frequency of the gas proportional valve can reduce the amount of gas supplied per unit time, thereby reducing the combustion intensity and preventing the surface temperature from continuing to rise.

[0093] Step b2: In response to the current surface temperature being less than the second temperature threshold, increase the gas injection frequency of the gas proportional valve. The second temperature threshold is lower than the first temperature threshold. The second temperature threshold is used to characterize the minimum allowable temperature during normal combustion of the burner.

[0094] It should be noted that increasing the gas injection frequency of the gas proportional valve can increase the gas supply, improve combustion intensity, and prevent unstable combustion or insufficient heat output caused by excessively low temperature.

[0095] For example, if the current surface temperature is within the range of the first temperature threshold and the second temperature threshold, then the current injection frequency can be maintained by appropriately increasing the gas injection frequency in the actual use scenario.

[0096] Taking a fully premixed gas water heater as an example, the normal stable combustion surface temperature of the burner can be in the range of 300°C to 480°C. Below 300°C, incomplete combustion or unstable flame is likely, while above 480°C, material aging will be accelerated. The first temperature threshold is the maximum allowable temperature when the burner is burning at normal temperature. When setting the first temperature threshold, factors such as the extreme temperature of the material can be considered, and a safety margin of 40°C to 50°C can be retained. Therefore, the first temperature threshold can be set to 460°C. The second temperature threshold is above the flameout critical temperature. When the critical temperature is 300°C, in order to ensure stable combustion of the burner and retain a safety margin of 30°C to 40°C, the second temperature threshold can be set to 330°C. Below the second temperature threshold, the gas injection frequency of the gas proportional valve is increased.

[0097] The gas water heater control method provided in this embodiment detects the current surface temperature of the burner and adjusts the gas injection frequency based on the relationship between the current surface temperature and different temperature thresholds. This achieves precise control of the injection quantity at different temperatures, improves combustion stability, and ensures the safety of the water heater, thus realizing a shift from passive protection to active defense.

[0098] Step S307: During the operation of the gas water heater, in response to the detection that the rate of change of the burner surface temperature exceeds the preset temperature change rate threshold, the fan speed is increased, the gas injection frequency of the gas proportional valve is reduced, or the gas proportional valve is controlled to stop injecting gas.

[0099] It should be noted that if the burner surface temperature rises abnormally, the system will automatically adjust the burner injection frequency or shut off the gas supply, while increasing the fan speed to purge residual gas and prevent backfire.

[0100] For example, when the rate of change of the burner surface temperature is detected to exceed a preset temperature change rate threshold, the fan speed can be adjusted to the maximum speed setting to avoid backfire and ensure the safe use of the gas water heater.

[0101] For example, the PWM injection frequency is first dynamically reduced or the gas supply is directly cut off by fuzzy logic to extend the cooling cycle and block heat accumulation. At the same time, the fan speed is forcibly increased to the maximum range instantly. The strong scouring force generated by the high-speed airflow is used to completely purge and expel the residual combustible gas in the combustion chamber within milliseconds, thereby quickly blocking the backfire path and restoring a safe state at the physical level.

[0102] The control method for a gas water heater provided in this embodiment increases the fan speed when the rate of change of the burner surface temperature exceeds a preset temperature change rate threshold, thereby avoiding backfire while ensuring the safe use of the gas water heater.

[0103] By constructing a dynamic air-fuel ratio model (DAFRAM) that integrates fuzzy logic and adaptive filtering, and combining a feedforward compensation mechanism and a pulse width modulation (PWM) injection strategy under extremely low load, the gas water heater achieves real-time closed-loop precise control of the air-fuel ratio and active suppression of backfire risk under all operating conditions.

[0104] Combination Figure 4 This describes an application example of a control method for a gas water heater. For example, Figure 4 This is a schematic diagram of the system framework of a gas water heater.

[0105] Using the set heat load as the input to the dynamic air-fuel ratio adaptive control system of the gas water heater, during combustion, a flue gas oxygen content sensor monitors flue gas oxygen content data, a gas outlet pressure sensor monitors the pressure difference data at the gas outlet, and a burner surface temperature sensor monitors the burner surface temperature data. Adaptive filtering technology is used to denoise the flue gas oxygen content data, pressure difference data, and burner surface temperature data, and the reliable signal is sent to the dynamic air-fuel ratio adaptive model, i.e., the preset fuzzy rule base in the above method embodiment. This model continuously corrects the air-fuel ratio target based on the denoised flue gas oxygen content data, pressure difference data, and burner surface temperature data. Combined with a feedforward compensation mechanism, i.e., the load change trend in the above method embodiment, the feedforward compensation amount is determined, thereby obtaining the fan speed and gas proportional valve opening. Based on this fan speed and gas proportional valve opening, the water heater is controlled, making the actual air-fuel ratio close to the optimal value. This achieves real-time closed-loop precise control of the air-fuel ratio of the gas water heater under all operating conditions and active suppression of backfire risk.

[0106] Key parameters during the combustion process are collected by multiple sensors, and the combustion state is intelligently adjusted by combining these parameters with control algorithms. The specific implementation steps are as follows: Sensor Acquisition Module: The system integrates a flue gas oxygen content sensor, a gas duct outlet pressure sensor, and a burner surface temperature sensor to collect key parameters during the combustion process in real time. Specifically, the flue gas oxygen content is used to indicate whether the air-fuel ratio is close to the ideal stoichiometric ratio; the pressure difference at the gas duct outlet is used to determine the trend of gas and air flow changes; and the temperature field data is used to identify whether the burner is in a flashback risk zone.

[0107] Sensor data preprocessing: To improve the accuracy and stability of the data, the system employs adaptive filtering technology to preprocess the acquired sensor data. This module uses algorithms such as Kalman filtering or wavelet transform to effectively eliminate sensor noise interference, improve the signal-to-noise ratio of the input data, and thus enhance the accuracy of the feedforward compensation mechanism.

[0108] Dynamic Air-Fuel Ratio Adaptive Model (DAFRAM) Construction: Based on preprocessed sensor data, the system constructs a DAFRAM model. This model introduces a fuzzy logic control mechanism. By constructing a fuzzy rule base, it fuzzifies the input oxygen content, pressure difference at the gas outlet, and temperature data, and dynamically calculates the current optimal air-fuel ratio through a fuzzy inference mechanism, outputting an air-fuel ratio deviation signal.

[0109] It should be noted that DAFRAM is a specific, highly integrated system architecture with a unique construction logic. First, the system uses Kalman filtering and adaptive wavelet transform to perform real-time denoising and feature extraction on the raw data from the oxygen sensor, gas duct outlet pressure sensor, and temperature field array, eliminating environmental noise interference and accurately identifying load change trends. Second, the processed oxygen content deviation, load change rate (dQ / dt), and burner surface temperature gradient or temperature change rate are mapped into fuzzy linguistic variables. Fuzzy inference is performed through a pre-set expert rule base, which introduces "load change trend" as a pre-judgment condition, thereby predicting the direction of air-fuel ratio deviation and outputting a basic correction amount before the combustion state deteriorates. Subsequently, the system superimposes feedforward compensation values ​​calculated based on the physical heat balance equation, and synchronously adjusts the variable frequency fan speed and gas proportional valve opening at millisecond speeds to achieve rapid response. Finally, the model has a built-in online learning mechanism to continuously monitor the convergence error between the actual oxygen content and the target value, and dynamically fine-tune the shape of the fuzzy membership function and the rule weights.

[0110] Feedforward compensation mechanism: When the user-set load changes, the system uses the gas outlet pressure sensor to predict the changing trends of gas and air flow rates, and adjusts the fan speed and gas proportional valve opening in advance to avoid combustion instability caused by sudden flow changes. With the support of adaptive filtering technology, this mechanism significantly improves the accuracy of feedforward compensation and the stability of the system response.

[0111] It should be noted that the gas outlet pressure sensor collects the pressure difference data ΔPgas at the outlet of the gas proportional valve in real time via high frequency (200Hz). After eliminating sensor noise using a Kalman filter algorithm, the instantaneous slope (i.e., derivative dP / dt) of the pressure difference over time is calculated as a "prior signal" for load abrupt changes. When the pressure difference change rate is detected to exceed the dynamic threshold and show a positive growth trend, the system immediately determines that the user is about to turn on or increase the water flow, based on the fact that the flow rate is proportional to the square root of the pressure difference. This triggers the feedforward compensation mechanism, which directly calculates the required valve opening increment and fan speed increase based on a preset nonlinear lookup table. Within tens of milliseconds before a significant change in the physical water flow, the system synchronously executes the "gas increase and air increase" command. Conversely, if a sharp drop in pressure difference is detected, it is determined to be a sudden decrease in load. The system immediately instructs the valve to reduce its opening and reduces the fan speed to the minimum safe threshold. This predictive process does not operate independently, but is fed into the DAFRAM fuzzy inference engine as a core input variable. It is logically coupled with real-time oxygen content deviation and burner temperature field data to make decisions. For example, when a load surge is predicted but the current oxygen content is already too high (risk of oxygen deficiency), the fuzzy rules will prioritize limiting the increase in gas opening and instead force a significant increase in fan speed to ensure that the air-fuel mixture ratio does not deviate from the safe range. This achieves gas-air synchronization within milliseconds, solving the risk of cold water shock or overheating caused by water temperature lag in traditional control.

[0112] Closed-loop feedback control: The air-fuel ratio deviation signal output by the DAFRAM model is sent to the closed-loop control module. Combined with the current operating status of the blower and the gas proportional valve, a new control command is calculated to ensure that the combustion process is always maintained near the optimal stoichiometric ratio.

[0113] It should be noted that after receiving the air-fuel ratio deviation signal from the model output, the DAFRAM closed-loop control module first inputs it into the fuzzy adaptive inference engine. This engine dynamically adjusts the three core parameters—proportional (Kp), integral (Ki), and derivative (Kd)—in real time based on the current error magnitude and rate of change, overcoming the nonlinear response differences of traditional fixed-parameter PID controllers under different load ranges (such as smoldering and high-fire). Subsequently, it combines an online adaptive algorithm to compensate for parameter drift caused by long-term operation of the combustion system (such as gas source fluctuations or component aging) in real time, ensuring the accuracy of the control model. Then, the fuzzy-optimized PID output is weighted and superimposed with the feedforward compensation, ultimately generating a control command that includes the fan speed correction value and the gas proportional valve opening correction value, driving the actuator to move.

[0114] Extremely low load control strategy: When the system detects that the current load is lower than the set threshold, the base fan speed is kept constant, and gas pulse width modulation (PWM) is used to control gas injection to maintain the minimum stable combustion state. The system also uses the burner surface temperature field data to determine in real time whether there is a risk of backfire.

[0115] It should be noted that the current load refers to the load calculated by the system based on real-time water flow, inlet water temperature, and user-set temperature, using the heat balance formula Q=Cp×ρ×Qwater×(Tset) The instantaneous required heat output power is calculated by Tin. The detection process involves the MCU collecting data from the water flow sensor and the inlet / outlet water temperature sensor, substituting them into the above physical model for real-time calculation, and comparing the calculation result with the preset minimum stable combustion threshold (20% of the rated power). Once the required heat load is detected to be continuously lower than this threshold without drastic fluctuations, the system determines that it has entered an extremely low load condition and automatically triggers the PWM control strategy to lock the fan speed to maintain the basic turbulent mixing environment.

[0116] The PWM pulse frequency is not a fixed value, but a variable dynamically and adaptively adjusted by the DAFRAM model based on the current load and the burner surface temperature field distribution. In the minimum fire mode, the frequency is typically low (10-15Hz) to prolong the single gas injection time, ensuring thorough mixing and preventing localized over-combustion or flameout caused by trace amounts of gas injection. When the system detects excessively high local temperatures on the burner plate, posing a risk of backfire, it actively reduces the frequency to increase the shutdown cooling time, utilizing the thermal inertia of the metal fibers for heat dissipation. Conversely, if the temperature is too low, causing flame instability, the frequency is appropriately increased to enhance thermal inertia and maintain combustion. This dynamic frequency adjustment mechanism based on fuzzy logic ensures stable combustion at minimum firepower while effectively avoiding backfire risks and suppressing noise.

[0117] Active backfire suppression mechanism: If the burner surface temperature rises abnormally, the system will automatically adjust the gas injection frequency or shut off the gas supply, while increasing the fan speed to purge residual gas and prevent backfire from occurring.

[0118] It should be noted that, firstly, the PWM injection frequency is dynamically reduced or the gas supply is directly cut off through fuzzy logic to extend the cooling cycle and block heat accumulation; at the same time, the fan speed is forcibly increased to the maximum range instantly, and the strong scouring force generated by the high-speed airflow is used to completely purge and expel the residual combustible gas in the combustion chamber within milliseconds, thereby quickly blocking the backfire path and restoring a safe state at the physical level.

[0119] The control method for gas water heaters provided in this embodiment achieves continuous and smooth adjustment from minimum to maximum flame, effectively solving the technical problems of unstable combustion state, inaccurate air-fuel ratio control, high nitrogen oxide emissions, and unstable thermal efficiency in traditional fully premixed combustion systems during load switching. At the same time, it improves the adaptability and stability of the system under complex operating conditions.

[0120] This embodiment provides a control method for a gas water heater, which constructs a dynamic air-fuel ratio adaptive model (DAFRAM) based on multi-sensor fusion. It integrates multi-dimensional data such as flue gas oxygen content, air / gas pressure difference, and burner surface temperature to achieve real-time closed-loop feedback control of the air-fuel ratio, breaking through the limitations of traditional static table lookup or single-parameter feedback.

[0121] A fuzzy logic control mechanism is introduced into the DAFRAM model. By constructing a fuzzy rule base, fuzzy reasoning is performed on input variables such as oxygen content deviation, pressure change rate, and temperature gradient, and the air-fuel ratio set value is dynamically adjusted, which significantly improves the system's ability to handle sensor uncertainties and nonlinear problems.

[0122] Adaptive filtering technology is used to preprocess sensor data, and Kalman filtering or wavelet denoising algorithms are applied to effectively eliminate noise interference, improve the data signal-to-noise ratio, provide high-quality input for feedforward compensation, and enhance control stability.

[0123] By introducing a feedforward compensation mechanism and using the gas outlet pressure sensor to predict load change trends, the fan speed and gas proportional valve opening are adjusted in advance before the user changes the settings, achieving "adjustment before combustion" and significantly shortening the response time.

[0124] Under extremely low load conditions, the basic fan speed is combined with the gas pulse width modulation (PWM) injection strategy to maintain the minimum stable air volume. The gas input is controlled by high-frequency pulses to solve the problem of combustion oscillation under low load.

[0125] By introducing a burner surface temperature field monitoring mechanism and deploying multiple temperature sensors or infrared thermal imaging devices, a temperature distribution map is constructed in real time. When an abnormal increase in local temperature is detected, a backfire suppression program is automatically activated, including reducing the gas injection frequency, increasing the fan speed to purge, or cutting off the gas supply, thus achieving an upgrade from "passive protection" to "active defense".

[0126] This embodiment also provides a control device for a gas water heater, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0127] This embodiment provides a control device for a gas water heater, such as... Figure 5 As shown, it includes: The data acquisition module 501 is used to acquire data on flue gas oxygen content, pressure difference at the gas outlet, surface temperature, and operating power of the burner during the combustion process. The first determining module 502 is used to determine the oxygen content deviation from the preset target oxygen content based on flue gas oxygen content data, determine the load change trend based on pressure difference data, calculate the load change rate based on operating power data, and calculate the temperature change rate based on surface temperature data. The reasoning module 503 is used to perform fuzzy reasoning on oxygen content deviation, load change rate and temperature change rate based on a preset fuzzy rule base to obtain air-fuel ratio deviation. The second determining module 504 is used to determine the feedforward compensation amount based on the load change trend; The adjustment module 505 is used to adjust the air intake volume of the air intake duct into the premixing chamber and the gas volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and the feedforward compensation amount.

[0128] In some alternative implementations, the first determining module 502 includes: The first determining unit is used to calculate the rate of change of pressure difference based on the pressure difference data and to determine the trend of the rate of change of pressure difference.

[0129] The second determining unit is used to determine that the load change trend is increasing when the rate of change of pressure difference is greater than the preset threshold for the rate of change of pressure difference and the trend of change is increasing.

[0130] The third determining unit is used to determine the load change trend as load reduction when the pressure difference change rate is greater than the preset pressure difference change rate threshold and the change trend is decreasing.

[0131] In some alternative implementations, the inference module 503 includes: The first reasoning unit is used to map oxygen content deviation, load change rate, and temperature change rate into fuzzy linguistic variables.

[0132] The second reasoning unit is used to perform fuzzy reasoning on the fuzzy linguistic variables corresponding to oxygen content deviation, load change rate and temperature change rate based on a preset fuzzy rule base, so as to obtain the air-fuel ratio deviation.

[0133] In some alternative implementations, the adjustment module 505 includes: The first regulating unit is used to determine the target valve opening regulation amount of the gas proportional valve and the target speed regulation amount of the fan based on the air-fuel ratio deviation and the feedforward compensation amount.

[0134] The feedforward compensation includes the first valve opening adjustment and the first speed adjustment.

[0135] In some alternative implementations, the first adjustment unit includes: The first regulating subunit is used to determine the second valve opening adjustment amount and the second speed adjustment amount based on the air-fuel ratio deviation.

[0136] The second regulating subunit is used to determine the target valve opening regulation amount based on the sum of the first valve opening regulation amount and the second valve opening regulation amount, and to determine the target speed regulation amount based on the sum of the first speed regulation amount and the second speed regulation amount. When the load change trend is that the load is increasing, the target valve opening regulation amount is used to increase the valve opening and the target speed regulation amount is used to increase the fan speed. When the load change trend is that the load is decreasing, the target valve opening regulation amount is used to decrease the valve opening and the target speed regulation amount is used to decrease the fan speed.

[0137] The second regulating unit is used to regulate the valve opening of the gas proportional valve based on the target valve opening regulation amount, and to regulate the fan speed based on the target speed regulation amount.

[0138] In some alternative embodiments, the device further includes: The first injection frequency adjustment module is used to maintain the current speed of the fan and adjust the gas injection frequency of the gas proportional valve based on the current surface temperature of the burner when the gas water heater is detected to be less than the preset heat output power threshold during operation.

[0139] In some alternative implementations, the first injection frequency adjustment module includes: The first injection adjustment unit is used to reduce the gas injection frequency of the gas proportional valve in response to the current surface temperature being greater than a first temperature threshold, wherein the first temperature threshold is used to characterize the maximum allowable temperature when the burner is in normal combustion.

[0140] The second injection adjustment unit is used to increase the gas injection frequency of the gas proportional valve in response to the current surface temperature being less than a second temperature threshold, wherein the second temperature threshold is lower than a first temperature threshold; the second temperature threshold is used to characterize the minimum allowable temperature when the burner is in normal combustion.

[0141] The second injection frequency adjustment module is used to increase the fan speed, reduce the gas injection frequency of the gas proportional valve, or control the gas proportional valve to stop injecting gas in response to the detection that the rate of change of the burner surface temperature exceeds the preset temperature change rate threshold during the operation of the gas water heater.

[0142] The control device for a gas water heater provided in this embodiment of the invention can execute the control method for a gas water heater provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0143] Figure 6 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention.

[0144] The following is a detailed reference. Figure 6 The diagram illustrates a structural schematic suitable for implementing a controller in an embodiment of the present invention. The controller may include a processor (e.g., a central processing unit, graphics processing unit, etc.) 601, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 602 or a program loaded from memory 608 into random access memory (RAM) 603. The RAM 603 also stores various programs and data required for controller operation. The processor 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0145] Typically, the following devices can be connected to I / O interface 605: input devices 606 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 607 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 608 including, for example, magnetic tapes, hard disks, etc.; and communication devices 609. Communication device 609 allows the controller to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 6 A controller with various devices is shown, but it should be understood that it is not required to implement or have all of the devices shown, and may alternatively implement or have more or fewer devices.

[0146] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 609, or installed from a memory 608, or installed from a ROM 602. When the computer program is executed by the processor 601, it performs the functions defined in the control method for a gas water heater according to embodiments of the present invention.

[0147] Figure 6The controller shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0148] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the control method for a gas water heater shown in the above embodiments is implemented.

[0149] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0150] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A control method for a gas water heater, the gas water heater comprising: The method comprises a burner, an air inlet duct, a gas combustion duct, and a premixing chamber, wherein the premixing chamber is connected to the burner, the air inlet duct, and the gas combustion duct, respectively. Air from the air inlet duct and gas from the gas combustion duct are mixed in the premixing chamber and then delivered to the burner for combustion. The method is characterized by comprising: Data on flue gas oxygen content, gas outlet pressure difference, burner surface temperature, and burner operating power are collected during the combustion process. The operating power of the burner during operation refers to the heat output power of the gas water heater. Based on the flue gas oxygen content data, the oxygen content deviation from the preset target oxygen content is determined; based on the pressure difference data, the load change trend is determined; based on the operating power data, the load change rate is calculated; and based on the surface temperature data, the temperature change rate is calculated. Based on a preset fuzzy rule base, fuzzy inference is performed on the oxygen content deviation, the load change rate, and the temperature change rate to obtain the air-fuel ratio deviation; Based on the load change trend, the feedforward compensation amount is determined, which includes a first valve opening adjustment amount and a first speed adjustment amount; The intake air volume of the intake air duct and the amount of gas entering the premixing chamber are adjusted based on the air-fuel ratio deviation and the feedforward compensation amount. The gas duct outlet is equipped with a gas proportional valve, and the air inlet is equipped with a fan. Adjusting the air intake volume of the air duct into the premixing chamber and the gas intake volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and the feedforward compensation amount includes: Based on the air-fuel ratio deviation and the feedforward compensation amount, the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan are determined; based on the air-fuel ratio deviation, the second valve opening adjustment amount and the second speed adjustment amount are determined. The valve opening of the gas proportional valve is adjusted based on the target valve opening adjustment amount, and the speed of the fan is adjusted based on the target speed adjustment amount.

2. The method according to claim 1, characterized in that, The process of performing fuzzy inference on the oxygen content deviation, the load change rate, and the temperature change rate based on a preset fuzzy rule base to obtain the air-fuel ratio deviation includes: The oxygen content deviation, the load change rate, and the temperature change rate are mapped to fuzzy linguistic variables; Based on a preset fuzzy rule base, fuzzy reasoning is performed on the fuzzy linguistic variables corresponding to the oxygen content deviation, the load change rate, and the temperature change rate to obtain the air-fuel ratio deviation.

3. The method according to claim 1, characterized in that, Determining the load change trend based on the pressure difference data includes: Calculate the rate of change of the pressure difference based on the pressure difference data, and determine the trend of the rate of change of the pressure difference. When the rate of change of the pressure difference is greater than a preset threshold for the rate of change of the pressure difference, and the trend of change is increasing, the load change trend is determined to be an increasing load. When the rate of change of the pressure difference is greater than a preset threshold for the rate of change of the pressure difference, and the trend of change is decreasing, the load change trend is determined to be a decrease in load.

4. The method according to claim 1, characterized in that, The step of determining the target valve opening adjustment of the gas proportional valve and the target speed adjustment of the fan based on the air-fuel ratio deviation and the feedforward compensation includes: The target valve opening adjustment amount is determined based on the sum of the first valve opening adjustment amount and the second valve opening adjustment amount, and the target speed adjustment amount is determined based on the sum of the first speed adjustment amount and the second speed adjustment amount. When the load change trend is increasing, the target valve opening adjustment amount is used to increase the valve opening, and the target speed adjustment amount is used to increase the fan speed. When the load change trend is decreasing, the target valve opening adjustment amount is used to decrease the valve opening, and the target speed adjustment amount is used to decrease the fan speed.

5. The method according to claim 1, characterized in that, The method further includes: During the operation of the gas water heater, in response to the detection that the heat output power of the gas water heater is less than a preset heat output power threshold, the current speed of the fan is maintained, and the gas injection frequency of the gas proportional valve is adjusted based on the current surface temperature of the burner.

6. The method according to claim 5, characterized in that, Adjusting the gas injection frequency of the gas proportional valve based on the current surface temperature of the burner includes: In response to the current surface temperature being greater than a first temperature threshold, the gas injection frequency of the gas proportional valve is reduced, where the first temperature threshold is used to characterize the maximum allowable temperature during normal combustion of the burner; In response to the current surface temperature being less than a second temperature threshold, the gas injection frequency of the gas proportional valve is increased, where the second temperature threshold is lower than the first temperature threshold; the second temperature threshold is used to characterize the minimum permissible temperature during normal combustion of the burner.

7. The method according to claim 5, characterized in that, The method further includes: During the operation of the gas water heater, in response to detecting that the rate of change of the surface temperature of the burner exceeds a preset temperature change rate threshold, the fan speed is increased, the gas injection frequency of the gas proportional valve is reduced, or the gas proportional valve is controlled to stop injecting gas.

8. A control device for a gas water heater, the gas water heater comprising: The device comprises a burner, an air inlet duct, a gas combustion duct, and a premixing chamber, wherein the premixing chamber is connected to the burner, the air inlet duct, and the gas combustion duct, respectively. The air from the air inlet duct and the gas combustion duct are mixed in the premixing chamber and then delivered to the burner for combustion. The device is characterized in that it includes: The data acquisition module is used to collect data on the oxygen content of flue gas, the pressure difference at the gas outlet, the surface temperature of the burner, and the operating power during the combustion process. The operating power of the burner during operation refers to the heat output power of the gas water heater. The first determining module is used to determine the oxygen content deviation from the preset target oxygen content based on the flue gas oxygen content data, determine the load change trend based on the pressure difference data, calculate the load change rate based on the operating power data, and calculate the temperature change rate based on the surface temperature data. The reasoning module is used to perform fuzzy reasoning on the oxygen content deviation, the load change rate, and the temperature change rate based on a preset fuzzy rule base to obtain the air-fuel ratio deviation. The second determining module is used to determine the feedforward compensation amount based on the load change trend, wherein the feedforward compensation amount includes the first valve opening adjustment amount and the first speed adjustment amount; An adjustment module is used to adjust the air intake volume of the air intake duct into the premixing chamber and the gas volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and the feedforward compensation amount. The gas duct outlet is equipped with a gas proportional valve, and the air inlet is equipped with a fan. Adjusting the air intake volume of the air duct into the premixing chamber and the gas intake volume of the gas duct into the premixing chamber based on the air-fuel ratio deviation and the feedforward compensation amount includes: Based on the air-fuel ratio deviation and the feedforward compensation amount, the target valve opening adjustment amount of the gas proportional valve and the target speed adjustment amount of the fan are determined; based on the air-fuel ratio deviation, the second valve opening adjustment amount and the second speed adjustment amount are determined. The valve opening of the gas proportional valve is adjusted based on the target valve opening adjustment amount, and the speed of the fan is adjusted based on the target speed adjustment amount.

9. A gas water heater, characterized in that, The gas water heater includes a burner, an air inlet duct, a gas duct, and a premixing chamber. The premixing chamber is connected to the burner, the air inlet duct, and the gas duct. The air from the air inlet duct and the gas from the gas duct are mixed in the premixing chamber and then delivered to the burner for combustion. The burner also includes a controller, which includes: A memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to perform the method of any one of claims 1 to 7.

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