Control method of gas water heater and gas water heater

Abstract

This invention relates to the field of hot water supply equipment technology, and discloses a control method and a gas water heater. The method includes: calculating the real-time theoretical current based on real-time inlet water temperature, target temperature, and real-time water flow; calculating the real-time compensation current of the gas water heater based on changes in the real-time predicted current when the gas water heater is in the variable temperature control stage; using the most recently calculated real-time compensation current as the target compensation current in response to the gas water heater entering the constant temperature control stage; calculating the target control current of the gas water heater based on the target compensation current, the real-time predicted current, and the real-time theoretical current, and adjusting the proportional valve current of the gas water heater based on the target control current. This uses the change in the real-time predicted current during the variable temperature control stage as the adjustment benchmark during the constant temperature control stage, achieving incremental output of the real-time predicted current, ensuring control stability, and employing parallel control of theoretical calculation and feedback control algorithms to improve response speed.

Description

Technical Field

[0001] This invention relates to the field of hot water supply equipment technology, and in particular to a control method for a gas water heater and a gas water heater. Background Technology

[0002] In the process of constant temperature control of water heaters, a combination of theoretical calculation and feedback control algorithms is typically used to control the outlet water temperature. First, a target load is calculated theoretically to control the heating of the gas water heater. When the outlet water temperature approaches the target temperature, a feedback control algorithm is used to control the outlet water temperature. However, when the load of the gas water heater changes, this method cannot perform feedforward control in a timely manner, resulting in significant temperature overshoot. Summary of the Invention

[0003] The first technical problem solved by this invention is to provide a control method for a gas water heater, which effectively solves the problems of not being able to perform feedforward control in a timely manner according to the load changes of the gas water heater and large temperature overshoot.

[0004] The second technical problem solved by this invention is to provide a gas water heater that effectively solves the problems of not being able to perform feedforward control in a timely manner according to the load changes of the gas water heater and large temperature overshoot.

[0005] The first technical problem mentioned above is solved by the following technical solution:

[0006] A method for controlling a gas water heater, the method comprising:

[0007] Obtain the real-time inlet water temperature, target temperature, and real-time water flow rate of the gas water heater;

[0008] Based on real-time inlet water temperature, target temperature and real-time water flow, the real-time theoretical current is calculated in real time.

[0009] When the gas water heater is in the variable temperature control stage, the real-time compensation current of the gas water heater is calculated in real time based on the real-time predicted current change output by the gas water heater's active disturbance rejection control algorithm.

[0010] In response to the gas water heater entering the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current.

[0011] When the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, real-time predicted current and real-time theoretical current, and the proportional valve current of the gas water heater is adjusted based on the target control current.

[0012] The control method for gas water heaters described in this invention has the following advantages compared to the prior art:

[0013] When the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, real-time predicted current, and real-time theoretical current. The proportional valve current of the gas water heater is then adjusted based on the target control current. This approach combines theoretical calculation with feedback control algorithms in parallel to control the gas water heater. When the load of the gas water heater changes, feedforward control can be implemented promptly, thereby improving response speed and preventing temperature overshoot. Simultaneously, the real-time compensation current of the gas water heater is calculated in real time based on the changes in the real-time predicted current output by the gas water heater's active disturbance rejection control algorithm. This allows for the statistical analysis of the changes in the predicted current during the variable temperature control stage. When the gas water heater enters the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current. The changes in the real-time predicted current during the variable temperature control stage serve as the adjustment benchmark for the constant temperature control stage. When calculating the target control current, the real-time predicted current can be converted into an incremental output, thus avoiding the problem of control signal superposition and incoordination between the real-time theoretical current and the real-time predicted current, ensuring control stability.

[0014] In one embodiment, based on the real-time predicted current change output by the active disturbance rejection control algorithm, the real-time compensation current is calculated in real time, including:

[0015]

[0016] in, This is the currently calculated real-time compensation current. This is the real-time compensation current obtained from the previous calculation. This is the latest real-time predicted current output by the active disturbance rejection control algorithm. This is the real-time predicted current output by the active disturbance rejection control algorithm in the previous iteration.

[0017] In one embodiment, the initial value of the real-time compensation current is zero, and the initial value of the real-time prediction current is zero.

[0018] In one embodiment, the target control current of the gas water heater is calculated in real time based on the target compensation current, the real-time predicted current, and the real-time theoretical current, including:

[0019]

[0020] Among them, I b To control the target current, For real-time theoretical current, To predict current in real time, I s The target compensation current.

[0021] In one embodiment, the real-time theoretical current is calculated based on the real-time inlet water temperature, target temperature, and real-time water flow rate, including:

[0022] The real-time theoretical load is determined based on the real-time inlet water temperature, target temperature, and real-time water flow rate.

[0023] The real-time theoretical current is determined based on the real-time theoretical load.

[0024] In one embodiment, the method further includes:

[0025] After the gas water heater is ignited, the real-time predicted current is calculated based on the active disturbance rejection control algorithm.

[0026] In one embodiment, the method further includes:

[0027] When the gas water heater is in the variable temperature control stage, the real-time theoretical current is used as the target control current, and the proportional valve current is adjusted based on the target control current.

[0028] In one embodiment, the method further includes:

[0029] When the gas water heater is in the constant temperature control stage, if the real-time theoretical load change of the gas water heater reaches the preset change value, the gas water heater will be controlled to enter the variable temperature control stage.

[0030] Alternatively, after the gas water heater is ignited, control the gas water heater to enter the variable temperature control stage.

[0031] In one embodiment, the method further includes:

[0032] When the gas water heater is in the variable temperature control stage, if the combustion time of the gas water heater reaches the preset time, or if the outlet water temperature of the gas water heater reaches the target temperature, the gas water heater will be controlled to enter the constant temperature control stage.

[0033] The second technical problem mentioned above is solved by the following technical solution:

[0034] A gas water heater includes: a controller, the controller being used in the control method of the gas water heater described in any of the above embodiments. Attached Figure Description

[0035] 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.

[0036] Figure 1 This is a flowchart illustrating the control method of a gas water heater according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the process for calculating the real-time theoretical current in the control method of a gas water heater according to an embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0040] 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0041] In the thermostatic control process of water heaters, a combination of theoretical calculation and feedback control algorithms is typically used to control the outlet water temperature. First, a target load is calculated theoretically to control the heating of the gas water heater. Then, when the outlet water temperature approaches the target temperature, a feedback control algorithm is employed to control the outlet water temperature. However, this method cannot provide timely feedforward control when the load of the gas water heater changes, resulting in significant temperature overshoot. Furthermore, due to the cascading delay of the control signal and the amplification of the theoretical calculation mismatch under dynamic conditions, this method suffers from slow response speed in the later stages of control, making it difficult to adjust quickly under large disturbances.

[0042] In related technologies, there is also a method that combines theoretical calculations with feedback control algorithms in parallel to control the outlet water temperature of a water heater. By superimposing the outputs of the theoretical calculations and the feedback control algorithm, the response speed is improved. However, this method directly superimposes the control signals output by the theoretical calculations and the feedback control algorithm, resulting in a lack of coordination between the two control methods. This easily leads to phase conflicts, ultimately causing output oscillations and temperature overshoot.

[0043] To address the aforementioned technical problems, this invention provides a control method for a gas water heater. When the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, real-time predicted current, and real-time theoretical current. The proportional valve current of the gas water heater is then adjusted based on the target control current. This method combines theoretical calculation with a feedback control algorithm in parallel to control the gas water heater. When the load of the gas water heater changes, feedforward control can be implemented promptly, thereby improving response speed and avoiding temperature overshoot. Simultaneously, the real-time compensation current of the gas water heater is calculated in real time based on the changes in the real-time predicted current output by the gas water heater's active disturbance rejection control algorithm. This allows for statistical analysis of the changes in the predicted current during the variable temperature control stage. When the gas water heater enters the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current. The changes in the real-time predicted current during the variable temperature control stage are then used as the adjustment benchmark for the constant temperature control stage. When calculating the target control current, the real-time predicted current can be converted into an incremental output, thereby avoiding the problem of control signal superposition and incoordination between the real-time theoretical current and the real-time predicted current, ensuring control stability.

[0044] The following is combined Figures 1 to 2 The following describes embodiments of the present invention.

[0045] According to an embodiment of the present invention, in one aspect, a control method for a gas water heater is provided. Figure 1 This is a flowchart illustrating the control method for a gas water heater according to an embodiment of the present invention, as shown below. Figure 1 As shown, the method may include the following steps:

[0046] Step S101: Obtain the real-time inlet water temperature, target temperature, and real-time water flow rate of the gas water heater.

[0047] In this embodiment of the invention, an inlet water temperature sensor and a water flow sensor are installed on the inlet pipe of the gas water heater. The inlet water temperature sensor detects the inlet water temperature of the gas water heater in real time to obtain the real-time inlet water temperature, and the water flow sensor detects the water flow of the gas water heater in real time to obtain the real-time water flow rate. Based on the user's settings for the gas water heater, a target temperature is obtained; the target temperature is the outlet water temperature of the gas water heater that the user expects.

[0048] Step S102: Calculate the real-time theoretical current based on the real-time inlet water temperature, target temperature, and real-time water flow rate.

[0049] In this embodiment of the invention, the real-time theoretical current is determined based on theoretical calculations. Specifically, based on the real-time inlet water temperature, target temperature, and real-time water flow rate, the heat load that the gas water heater needs to provide to achieve the target outlet water temperature can be determined, i.e., the real-time theoretical load. Then, based on the real-time theoretical load, the current of the proportional valve required for the gas water heater to provide the real-time theoretical load is calculated, i.e., the real-time theoretical current.

[0050] Step S103: When the gas water heater is in the variable temperature control stage, the real-time compensation current of the gas water heater is calculated in real time based on the real-time predicted current change output by the gas water heater's active disturbance rejection control algorithm.

[0051] In this embodiment of the invention, the variable temperature control stage of the gas water heater refers to the change in the target load of the gas water heater, which is mainly caused by changes in the target temperature or water flow rate. For example, the user changes the target temperature, causing the load required for the gas water heater to reach the target temperature to change.

[0052] In this embodiment of the invention, when the gas water heater is in the variable temperature control stage, the changes in the real-time predicted current output by the active disturbance rejection control algorithm are statistically analyzed according to the first calculation cycle to calculate the real-time compensation current. The real-time predicted current is the target current value of the proportional valve current calculated based on the estimation and compensation of disturbance changes in the gas water heater by the active disturbance rejection control algorithm. The real-time predicted current is a positional parameter, meaning that the output of the active disturbance rejection control algorithm is the current value that the proportional valve current needs to be adjusted to achieve.

[0053] In one embodiment, the change in the real-time predicted current during the temperature control phase can be used as the real-time compensation current, thereby realizing the statistics of the change in the real-time predicted current during the temperature control phase. In this case, the first calculation cycle of the real-time compensation current is consistent with the duration of the temperature control phase.

[0054] In one embodiment, after the gas water heater is ignited, the real-time predicted current is calculated in real time based on the active disturbance rejection control algorithm. That is, after the gas water heater is ignited and starts heating, regardless of the state or control stage of the gas water heater, the active disturbance rejection control algorithm always outputs the real-time predicted current until the gas water heater is turned off.

[0055] It should be noted that, for example, in this embodiment, an active disturbance rejection control algorithm is used as the feedback control algorithm. However, those skilled in the art will know that the feedback control algorithm can also be other algorithms such as PID control algorithm, and no specific limitation is made here.

[0056] Step S104: In response to the gas water heater entering the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current.

[0057] In this embodiment of the invention, the constant temperature control stage of the gas water heater refers to the stage of maintaining the outlet water temperature of the gas water heater near the target temperature; when the outlet water temperature of the gas water heater reaches or approaches the target temperature, the gas water heater is controlled to enter the constant temperature control stage.

[0058] In this embodiment of the invention, in response to the gas water heater entering the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current, that is, the last calculated real-time compensation current in the variable temperature control stage is used as the target compensation current. The target compensation current can represent the overall change of the real-time predicted current in the variable temperature control stage. Therefore, when calculating the target control current of the gas water heater, the real-time predicted current can be calculated based on the overall change of the real-time predicted current in the variable temperature control stage, thereby converting the positional real-time predicted current into an incremental parameter.

[0059] Step S105: When the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, the real-time predicted current and the real-time theoretical current, and the proportional valve current of the gas water heater is adjusted based on the target control current.

[0060] In this embodiment of the invention, when the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, the real-time predicted current, and the real-time theoretical current. On the one hand, the position-based real-time predicted current is converted into an incremental parameter through the target compensation current. On the other hand, the real-time predicted current is combined with the real-time theoretical current to realize the parallel control of the gas water heater by theoretical calculation and feedback control. This improves the response speed while avoiding the problem of control signal superposition and incoordination, and ensures control stability.

[0061] In this embodiment of the invention, after calculating the target control current, the proportional valve current of the gas water heater is adjusted to the target control current, thereby realizing the control of the gas water heater in the constant temperature control stage.

[0062] In one embodiment, Figure 2 A flowchart illustrating the calculation of real-time theoretical current in the control method for a gas water heater according to an embodiment of the present invention is shown below. Figure 2 As shown, step S102 above, which calculates the real-time theoretical current based on the real-time inlet water temperature, target temperature, and real-time water flow rate, may include the following steps:

[0063] Step S201: Determine the real-time theoretical load based on the real-time inlet water temperature, target temperature, and real-time water flow rate.

[0064] In this embodiment of the invention, the real-time theoretical load is determined based on the real-time inlet water temperature, the target temperature, and the real-time water flow rate, as shown in the following formula (1):

[0065] P = (T) s -T i )×Q formula (1)

[0066] Where P is the real-time theoretical load, and T s For the target temperature, T i For real-time inlet water temperature, T i This represents the real-time water flow rate.

[0067] Step S202: Determine the real-time theoretical current based on the real-time theoretical load.

[0068] In this embodiment of the invention, the gas flow rate required by the gas water heater to reach the real-time theoretical current load can be determined based on the gas calorific value and gas efficiency, and then the real-time theoretical current can be determined based on the mapping relationship between the gas flow rate and the proportional valve current.

[0069] In one embodiment, in step S103 above, the real-time compensation current can be calculated in real time using the following formula (2):

[0070]

[0071] in, This is the currently calculated real-time compensation current. This is the real-time compensation current obtained from the previous calculation. This is the latest real-time predicted current output by the active disturbance rejection control algorithm. This is the real-time predicted current output by the active disturbance rejection control algorithm in the previous iteration.

[0072] In one embodiment, after the gas water heater is ignited, the real-time predicted current and the real-time theoretical current are calculated separately according to the second calculation cycle. This aligns the timing of the real-time predicted current and the real-time theoretical current, avoiding the situation where the signals are out of phase when combining theoretical calculations and feedback control. Accordingly, This is the real-time compensation current being calculated in the current first calculation cycle. This refers to the real-time compensation current calculated in the previous first calculation cycle of the current first calculation cycle; This represents the real-time predicted current output by the active disturbance rejection control algorithm in the most recent second calculation cycle. In order to be in The real-time predicted current output by the active disturbance rejection control algorithm in the first and second calculation cycles.

[0073] In one embodiment, the duration of the first calculation cycle and the second calculation cycle can be set according to actual application requirements. They can be set to the same duration or different durations, without any specific restrictions.

[0074] In one embodiment, the initial value of the real-time compensation current and the initial value of the real-time prediction current are both zero. During the subsequent cyclic control process of the gas water heater—that is, after the first entry into the variable temperature control stage—the gas water heater cycles through constant temperature control and variable temperature control stages based on the real-time theoretical load and outlet water temperature changes of the gas water heater. When the gas water heater enters the variable temperature control stage, the real-time compensation current is calculated in real-time based on the above formula, and the real-time prediction current is obtained based on the output of the active disturbance rejection control algorithm.

[0075] In one embodiment, when the gas water heater first enters the variable temperature control stage after ignition, the value of the real-time predicted current is set to the initial value. To avoid excessive fluctuations in the target load leading to inaccurate target compensation current, the real-time compensation current can be reset to the initial value each time the variable temperature control stage is entered. To ensure the continuity of control, the value of the real-time compensation current can be set to the initial value when the gas water heater first enters the variable temperature control stage after ignition.

[0076] According to the above formula (2), In reality, the real-time predicted current is the inverse of the difference between the most recent output real-time predicted current and its previous output real-time predicted current; that is, the inverse of the change in the most recent real-time predicted current. Correspondingly, the real-time compensation current can be represented by subtracting the change in the most recent real-time predicted current from the previously calculated real-time compensation current. In other words, it represents the difference between the real-time predicted current output when entering the variable temperature control stage and the most recent output real-time predicted current; that is, the inverse of the change in the real-time predicted current from the most recent entry into the variable temperature control stage to the current time. Therefore, the change in the real-time predicted current during the variable temperature control stage can be accumulated through the real-time compensation current. When the gas water heater transitions from the variable temperature control stage to the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current, thus using the inverse of the change in the real-time predicted current throughout the entire variable temperature control stage as the target compensation current.

[0077] In one embodiment, in step S105 above, the target control current can be calculated in real time using the following formula (3):

[0078]

[0079] Among them, I b To control the target current, For real-time theoretical current, To predict current in real time, I s The target compensation current.

[0080] According to the above formula (3), on the one hand, by adding the real-time predicted current to the target compensation current, the changes generated in the previous control stage in the real-time predicted current can be removed, thereby converting the real-time predicted current into an incremental parameter; on the other hand, by adding the real-time predicted current to the real-time theoretical current, the parallel control of theoretical calculation and feedback control algorithm can be realized, thereby using theoretical calculation to determine the control reference and using the incremental parameter of the feedback control algorithm to provide incremental correction, thereby performing dynamic disturbance compensation on the basis of the static reference calculated by theory, and ensuring the stability of control.

[0081] In the above embodiment, when the gas water heater is in the variable temperature control stage, the real-time theoretical current is used as the target control current, and the proportional valve current is adjusted based on the target control current. Thus, the operation of the gas water heater is controlled by theoretical calculation during the variable temperature control stage, thereby achieving rapid adjustment of the outlet water temperature of the gas water heater.

[0082] In the above embodiments, when the gas water heater is in the constant temperature control stage, if the change in the real-time theoretical load of the gas water heater reaches a preset change value, the gas water heater is controlled to enter the variable temperature control stage; or, after the gas water heater is ignited, the gas water heater is controlled to enter the variable temperature control stage. Thus, the gas water heater can quickly respond and enter the variable temperature control stage after its operating conditions change, so as to rapidly adjust the outlet water temperature.

[0083] In the above embodiment, when the gas water heater is in the variable temperature control stage, if the combustion time of the gas water heater reaches the preset time, or if the outlet water temperature of the gas water heater reaches the target temperature, the gas water heater is controlled to enter the constant temperature control stage. The preset time is an empirical value and can be set to 10 seconds, or determined based on the heating performance of the gas water heater in past operations.

[0084] The control method for a gas water heater provided in this invention calculates the target control current of the gas water heater in real time based on the target compensation current, real-time predicted current, and real-time theoretical current when the gas water heater is in the constant temperature control stage. The proportional valve current of the gas water heater is then adjusted based on the target control current. This method combines theoretical calculation with a feedback control algorithm in parallel to control the gas water heater. When the load of the gas water heater changes, feedforward control can be performed promptly, thereby improving response speed and avoiding temperature overshoot. Simultaneously, the real-time compensation current of the gas water heater is calculated in real time based on the changes in the real-time predicted current output by the gas water heater's active disturbance rejection control algorithm. This allows for statistical analysis of the changes in the predicted current during the variable temperature control stage. When the gas water heater enters the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current. The changes in the real-time predicted current during the variable temperature control stage are then used as the adjustment benchmark for the constant temperature control stage. When calculating the target control current, the real-time predicted current can be converted into an incremental output, thereby avoiding the problem of control signal superposition and incoordination between the real-time theoretical current and the real-time predicted current, ensuring control stability.

[0085] According to an embodiment of the present invention, in another aspect, a gas water heater is also provided, comprising: a controller, the controller being used for the control method of the gas water heater described in any of the above embodiments.

[0086] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0087] The specific embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A control method for a gas water heater, characterized in that, The method includes: The real-time inlet water temperature, target temperature, and real-time water flow rate of the gas water heater are obtained. Based on the real-time inlet water temperature, the target temperature, and the real-time water flow rate, the real-time theoretical current is calculated in real time. When the gas water heater is in the variable temperature control stage, the real-time compensation current of the gas water heater is calculated in real time based on the real-time predicted current change output by the active disturbance rejection control algorithm of the gas water heater. In response to the gas water heater entering the constant temperature control stage, the most recently calculated real-time compensation current is used as the target compensation current. When the gas water heater is in the constant temperature control stage, the target control current of the gas water heater is calculated in real time based on the target compensation current, the real-time predicted current and the real-time theoretical current, and the proportional valve current of the gas water heater is adjusted based on the target control current.

2. The method according to claim 1, characterized in that, The real-time predicted current change based on the active disturbance rejection control algorithm output, and the real-time compensation current calculation, include: in, This is the currently calculated real-time compensation current. This is the real-time compensation current obtained from the previous calculation. This refers to the latest real-time predicted current output by the active disturbance rejection control algorithm. The current is the real-time predicted current output by the active disturbance rejection control algorithm in the previous iteration.

3. The method according to claim 2, characterized in that, The initial value of the real-time compensation current is zero, and the initial value of the real-time prediction current is zero.

4. The method according to claim 1, characterized in that, The step of calculating the target control current of the gas water heater in real time based on the target compensation current, the real-time predicted current, and the real-time theoretical current includes: Among them, I b The target control current, The real-time theoretical current, For the real-time predicted current, I s The target compensation current.

5. The method according to claim 1, characterized in that, The real-time theoretical current calculation based on the real-time inlet water temperature, the target temperature, and the real-time water flow rate includes: Based on the real-time inlet water temperature, the target temperature, and the real-time water flow rate, the real-time theoretical load is determined; The real-time theoretical current is determined based on the real-time theoretical load.

6. The method according to claim 1, characterized in that, The method further includes: After the gas water heater is ignited, the real-time predicted current is calculated in real time based on the active disturbance rejection control algorithm.

7. The method according to claim 1, characterized in that, The method further includes: When the gas water heater is in the variable temperature control stage, the real-time theoretical current is used as the target control current, and the proportional valve current is adjusted based on the target control current.

8. The method according to claim 1, characterized in that, The method further includes: When the gas water heater is in the constant temperature control stage, if the change in the real-time theoretical load of the gas water heater reaches the preset change value, the gas water heater will be controlled to enter the variable temperature control stage. Alternatively, after the gas water heater is ignited, the gas water heater can be controlled to enter a variable temperature control phase.

9. The method according to claim 1, characterized in that, The method further includes: When the gas water heater is in the variable temperature control stage, if the combustion time of the gas water heater reaches the preset time, or if the outlet water temperature of the gas water heater reaches the target temperature, then the gas water heater is controlled to enter the constant temperature control stage.

10. A gas-fired water heater, characterized in that, include: A controller for performing the control method for a gas water heater as described in any one of claims 1 to 9.

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