Method and system for preventing dry boil of an appliance

Abstract

The present application relates to a method and system for preventing dry burning of household appliances, comprising the following steps: powering on the system; collecting the initial temperature T0 of the liquid in the container body by the first temperature sensor, comparing the initial temperature T0 with the preset temperature T 预设 ; if T0 预设 , heating the liquid in the container body in a multi-stage heating mode; if T0 预设 , heating the liquid in the container body in a constant temperature holding mode. By using the multi-stage heating mode first, calculating the slope of the temperature rising curve after each stage of heating, and determining whether the container body is dry, this method is less affected by the surrounding heat source, has high recognition accuracy, and has short detection time interval and fast response for each stage, ensuring the safety of the household appliance while quickly heating the liquid, and is especially suitable for heating liquid drinks.

Description

Technical Field

[0001] This invention relates to the field of home appliance temperature control technology, and in particular to a method and system for protecting home appliances from dry burning. Background Technology

[0002] Home appliances with heating functions, such as electric kettles, need to safely and accurately heat milk to the set temperature and maintain it within a certain constant temperature range.

[0003] Traditional home appliances typically have only one temperature switch, relying on a fixed temperature setting for detection. This makes them prone to false alarms or missed alarms due to interference from surrounding heat sources or their own inherent errors, resulting in weak dry-burn detection capabilities. Furthermore, because empty cups heat up rapidly, relying solely on the temperature setting has a certain lag. A sharp increase in both the appliance and food temperatures can lead to appliance malfunction or damage, causing the dry-burn protection function to fail, and posing safety hazards such as burns to food or users, thus negatively impacting the user experience.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a method and system for preventing dry burning of household appliances, in order to solve the problems of weak dry burning identification capabilities, delayed judgment time, easy misjudgment and missed judgment, as well as safety hazards such as damage to equipment, burns to food, and burns to users.

[0006] The technical solution adopted in this invention is as follows: A method for preventing dry burning of household appliances, comprising the following steps: System power on; The first temperature sensor acquires the initial temperature T0 of the liquid inside the container, and compares the initial temperature T0 with the preset temperature T. 预设 Compare; If T0 < T 预设 Heating the liquid inside the container using a multi-stage heating mode includes the following steps: The heating element heats up at the set maximum PWM duty cycle value; At preset intervals, the first temperature sensor collects the temperature of the liquid inside the container and calculates the slope of the heating curve. If the slope of the heating curve is within the preset range, then reduce the PWM duty cycle value of the heating element; If the slope of the heating curve is greater than the preset range, it is determined that the container is dry-burning and the heating element is de-energized.

[0007] A further technical solution involves heating the liquid inside the container using a multi-stage heating mode, including the following steps: First stage heating: Heating is performed using the first PWM duty cycle value. At intervals of t1, the first temperature sensor collects the temperature T1 and calculates the temperature rise slope k1 from T0 to T1. If k1 ≥ 0.4, it is determined that the container is dry-burning, and the heating element is powered off. If 0.4 > k1 ≥ 0.2, it is determined that the water content in the container is low, and the process jumps to the third stage heating. If k1 < 0.2, it is determined that the water content in the container is high, and the process jumps to the second stage heating. Second stage heating: Heating is performed with the second PWM duty cycle value. At intervals of t2, the first temperature sensor collects the temperature T2 and calculates the temperature rise slope k2 from T1 to T2. If 0.4 > k2 ≥ 0.2, it is determined that the water volume in the container is low, and the process jumps to the third stage heating. If k2 < 0.2, it is determined that the water volume in the container is high, and the process jumps to the third stage heating. The third stage of heating: Heating is performed using the third PWM duty cycle. At intervals of t3, the first temperature sensor collects the temperature T3 and calculates the temperature rise slope k3 from T2 to T3. If k3 ≥ 0.4, it is determined that the container is dry-burning, and the heating element 2 is powered off. If 0.4 > k3 ≥ 0.2, it is determined that there is little water in the container, and the process jumps to the fourth stage of heating. If k3 < 0.2, it is determined that there is a lot of water in container 1, and the process jumps to the fourth stage of heating. Fourth stage heating: Heating is performed with the fourth PWM duty cycle value. At an interval of t4, the first temperature sensor collects the temperature T4 and calculates the temperature rise slope k4 from T3 to T4. If k4≥0.4, it is determined that the container is dry-burning and the heating element is powered off. If k4<0.4, it is determined that the water volume in the container is normal and it switches to the constant temperature heat preservation mode to heat the liquid in the container. Among them, the duty cycle values ​​of the first PWM, the second PWM, the third PWM, and the fourth PWM decrease sequentially.

[0008] The further technical solution is as follows: the first PWM duty cycle is 100% and the heating time is 60s; the second PWM duty cycle is 80% and the heating time is 120s; the third PWM duty cycle is 50% and the heating time is 120s; the fourth PWM duty cycle is 30% and the heating time is 60s.

[0009] Its further technical solution is that if T0 < T 预设 After the step of heating the liquid inside the container using a multi-stage heating mode, the process also includes the following steps: The process continues until the PWM duty cycle of the heating element drops to the set minimum value, at which point it switches to a constant temperature insulation mode to heat the liquid inside the container. If T0≥T 预设When the PWM duty cycle of the heating element drops to the set minimum value, the liquid in the container is heated in a constant temperature insulation mode. Heating the liquid inside the container using a constant temperature insulation mode includes the following steps: The heating element heats at the set minimum PWM duty cycle value; The first temperature sensor collects the current temperature T in real time. 当前 ; If T 当前 ≥T 预设 If this happens, the heating element will stop heating; If T 当前 <T 预设范围 If this occurs, the heating element will restart.

[0010] A further technical solution is that the formula for calculating the slope of the heating curve is: k= ; Among them, T 上一时刻 The temperature last collected by the first temperature sensor. t is the time interval between two temperature acquisitions.

[0011] A further technical solution involves determining whether the container is dry-burning if the slope of the heating curve is greater than a preset range. When the first temperature sensor detects that the slope of the heating curve is greater than the preset range for the first time, the system marks it as "suspected dry burning state" and repeats the calculation of the slope of the heating curve in the next three acquisition cycles; only when the slope of the heating curve is greater than the preset range for three consecutive times is it determined that the container is dry burning and the heating element is powered off.

[0012] A further technical solution includes the following steps after the system power-on process: The third temperature sensor collects the ambient temperature T. env The dry-burning threshold k is dynamically adjusted, and the dry-burning threshold k satisfies the following formula: k = 0.4 - 0.01 × (25℃ - T) env ).

[0013] A further technical solution is that, after the system power-on step, a failure detection step is also included, which includes: The resistance value across the first temperature sensor is detected. If it is within the set value range, it is considered normal. If it is greater than the set value, it is considered that the first temperature sensor is open-circuited. If it is less than the set value, it is considered that the first temperature sensor is short-circuited. After determining that the container body is dry-burning, the process also includes a heating element abnormal conduction detection step, which includes: If the first temperature sensor detects that the current temperature is still rising by more than 3°C / min after the heating element is powered off, the system power supply will be immediately disconnected. After the system power-on procedure, an over-temperature detection procedure is also included, which includes: When the first temperature sensor detects that the current temperature exceeds 45°C, the power supply to the heating element is immediately disconnected.

[0014] The present invention also discloses a system for implementing the aforementioned method for preventing dry burning of household appliances. The system includes a container body, a heating element disposed at the bottom of the inner side of the container body, a first temperature sensor embedded at the upper end of the heating element, and a heat insulation plate disposed between the heating element and the first temperature sensor. The system also includes a controller, which is electrically connected to the heating element and the first temperature sensor.

[0015] A further technical solution is that a second temperature sensor is provided at the lower end of the heating element. The second temperature sensor is a mechanical temperature sensor with a trigger temperature of 120°C. The first temperature sensor is an NTC temperature sensor. The heating element is made of PTC ceramic with a Curie point temperature of 120°C.

[0016] The beneficial effects of the embodiments of the present invention are as follows: (i) The appliance dry-burn protection method of the present invention adopts a multi-stage heating method. After each stage of heating, the slope of the heating curve is calculated and it is determined whether the container is dry-burning. This method is not easily affected by the surrounding heat source, has a high accuracy rate, and the detection time interval between each stage is short and the response is fast. It ensures the safety of the appliance operation while rapidly heating the liquid, and is especially suitable for heating liquid beverages.

[0017] (ii) Furthermore, this application adopts a multi-stage heating mode combined with a constant temperature heat preservation mode. The multi-stage heating mode determines the water volume by calculating the slope of the temperature rise curve. In the initial state, when the water volume is large and the temperature is low, the PWM duty cycle can be used for heating for a long time to ensure rapid temperature rise. When the water volume is low, the PWM duty cycle is reduced quickly and the heating time is reduced to ensure rapid heating to the set temperature while reducing the possibility of the liquid in the container being boiled dry, reducing dry burning time, and extending the service life of the appliance.

[0018] (III) Furthermore, a triple overheat protection system is adopted. The first layer utilizes the self-limiting temperature physical properties of PTC ceramic in the heating element, automatically reducing power when the temperature exceeds the limit. The second layer uses a first temperature sensor to collect the temperature, disconnecting the power supply to the heating element when the temperature exceeds the limit. The third layer uses a mechanical temperature sensor at the bottom of the heating element, triggering a mechanical action to disconnect the circuit when the temperature exceeds the limit. By setting up a triple overheat protection system, it is ensured that the failure of any single component will not affect the normal operation of the system, resulting in high safety and reliability. Attached Figure Description

[0019] Figure 1This is a flowchart of the household appliance anti-dry-burning protection method of the present invention.

[0020] Figure 2 The data graph shows the process of heating 240ml of milk using the appliance anti-dry-burning protection method of the present invention.

[0021] Figure 3 The data graph shows the process of heating 120ml of milk using the appliance anti-dry-burning protection method of the present invention.

[0022] Figure 4 This is a structural diagram of the system of the present invention.

[0023] Figure 5 This is a connection diagram of the system of the present invention.

[0024] In the picture: 1. Container body; 2. Heating element; 3. Heat insulation plate; 4. First temperature sensor; 5. Second temperature sensor; 6. Third temperature sensor; 7. Controller. Detailed Implementation

[0025] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0026] First embodiment: This embodiment discloses a method for protecting household appliances from dry burning.

[0027] Figure 1 This is a flowchart of the household appliance anti-dry-burning protection method of the present invention. Figure 1 As shown, the method for protecting home appliances from dry burning includes the following steps: Step S1: Power on the system.

[0028] Step S2: The first temperature sensor 4 collects the initial temperature T0 of the liquid inside container 1, and compares the initial temperature T0 with the preset temperature T... 预设 Compare them.

[0029] Step S3, if T0 < T 预设 The liquid inside container 1 is heated using a multi-stage heating mode, which includes the following steps: Heating element 2 heats the components at the set maximum PWM duty cycle value.

[0030] At preset intervals, the first temperature sensor 4 collects the temperature of the liquid inside container 1 and calculates the slope of the heating curve.

[0031] If the slope of the heating curve is within the preset range, then reduce the PWM duty cycle value of the heating element 2.

[0032] If the slope of the heating curve is greater than the preset range, it is determined that container 1 is dry-burning and heating element 2 is de-energized.

[0033] Until the PWM duty cycle of the heating element 2 drops to the set minimum value, it switches to constant temperature insulation mode to heat the liquid in the container 1.

[0034] Specifically, the steps for heating the liquid inside container 1 using a multi-stage heating mode include: Step S31, First stage heating: Heating is performed with the first PWM duty cycle value. At intervals of t1, the first temperature sensor 4 collects the temperature T1 and calculates the temperature rise slope k1 from T0 to T1. If k1 ≥ 0.4, it is determined that container 1 is dry-burning, and the heating element 2 is powered off. If 0.4 > k1 ≥ 0.2, it is determined that the water volume in container 1 is low, and the process jumps to the third stage heating. If k1 < 0.2, it is determined that the water volume in container 1 is high, and the process jumps to the second stage heating.

[0035] Step S32, Second stage heating: Heating is performed with the second PWM duty cycle value. At intervals of t2, the first temperature sensor 4 collects the temperature T2 and calculates the temperature rise slope k2 from T1 to T2. If 0.4 > k2 ≥ 0.2, it is determined that the water volume in container 1 is low, and the process jumps to the third stage heating. If k2 < 0.2, it is determined that the water volume in container 1 is high, and the process jumps to the third stage heating.

[0036] Step S33, Third stage heating: Heating is performed with the third PWM duty cycle value. At intervals of t3, the first temperature sensor 4 collects the temperature T3 and calculates the temperature rise slope k3 from T2 to T3. If k3 ≥ 0.4, it is determined that container 1 is dry-burning, and heating element 2 is de-energized. If 0.4 > k3 ≥ 0.2, it is determined that the water volume in container 1 is low, and the process jumps to the fourth stage heating. If k3 < 0.2, it is determined that the water volume in container 1 is high, and the process jumps to the fourth stage heating.

[0037] Step S34, fourth stage heating: Heating is performed with the fourth PWM duty cycle value. At intervals of t4, the first temperature sensor 4 collects the temperature T4 and calculates the temperature rise slope k4 from T3 to T4. If k4 ≥ 0.4, it is determined that the container 1 is dry-burning, and the heating element 2 is powered off. If k4 < 0.4, it is determined that the water volume in the container 1 is normal, and the process switches to constant temperature heat preservation mode to heat the liquid in the container 1.

[0038] The first PWM duty cycle is 100% with a heating time of 60 seconds. The second PWM duty cycle is 80% with a heating time of 120 seconds. The third PWM duty cycle is 50% with a heating time of 120 seconds. The fourth PWM duty cycle is 30% with a heating time of 60 seconds.

[0039] The formula for calculating the slope of the heating curve is: k= ; Among them, T 上一时刻 The temperature measured by the first temperature sensor 4 in the previous test. t is the time interval between two temperature acquisitions.

[0040] Step S4, if T0≥T 预设 Heating the liquid inside container 1 using a constant temperature insulation mode includes the following steps: In step S41, the heating element 2 heats the components at the set minimum PWM duty cycle value.

[0041] Step S42, the first temperature sensor 4 collects the current temperature T in real time. 当前 .

[0042] Step S43, if T 当前 ≥T 预设 If the heating element 2 stops heating, then the heating element 2 will stop heating.

[0043] Step S44, if T 当前 <T 预设范围 Then the heating element 2 will restart.

[0044] Specifically, in the step of heating the liquid inside container 1 using a constant temperature insulation mode, heating is performed using the fifth PWM duty cycle value, which is 10%, the lowest PWM duty cycle value. The first temperature sensor 4 collects the temperature T5 in real time at a frequency of 10Hz, and the controller 7 can dynamically fine-tune the PWM duty cycle. When T5 ≥ 37℃, heating of heating element 2 is immediately stopped. When the temperature drops to 34℃, heating of heating element 2 is restarted to stabilize the temperature within the range of 37℃ ± 3℃.

[0045] Preferably, the temperature collected by the first temperature sensor 4 is processed using a sliding window averaging filter. Specifically, a sliding window of length 5 is used to preprocess the continuously collected temperature data, calculate the average value as the effective temperature value, and eliminate random noise and electromagnetic interference.

[0046] Furthermore, if the slope of the heating curve is greater than a preset range, the steps to determine if container 1 is dry-burning include: When the first temperature sensor 4 detects for the first time that the slope of the heating curve is greater than the preset range, the system marks it as "suspected dry burning state" and repeats the calculation of the slope of the heating curve in the next three acquisition cycles, i.e., 300ms. Only when the slope of the heating curve is greater than the preset range for three consecutive times is it determined that the container body 1 is dry burning and the heating element 2 is de-energized.

[0047] After determining that the container body 1 is dry-burning, the process also includes a step to detect abnormal continuity of heating element 2. The step to detect abnormal continuity of heating element 2 includes: After the heating element 2 is powered off, if the first temperature sensor 4 detects that the current temperature is still rising by more than 3°C / min, the system power supply will be immediately disconnected.

[0048] Furthermore, after the system power-on step, the following steps are also included: Step S11, the third temperature sensor 6 collects the ambient temperature T. env The dry-burning threshold k is dynamically adjusted, and the dry-burning threshold k satisfies the following formula: k = 1.0 - 0.01 × (25℃ - T) env By adjusting the k value to adapt to different usage scenarios under varying ambient temperatures, misjudgments and missed judgments can be avoided.

[0049] Following the system power-on procedure, a failure detection step is also included, which includes: Step S12: Detect the resistance value across the first temperature sensor 4. If it is within the set value range, it is considered normal. If it is greater than the set value, it is considered that the first temperature sensor 4 is open-circuited. If it is less than the set value, it is considered that the first temperature sensor 4 is short-circuited.

[0050] Specifically, if the resistance value across the first temperature sensor 4 is greater than 100kΩ, it is determined that the first temperature sensor 4 is open-circuited. If the resistance value across the first temperature sensor 4 is less than 100Ω, it is determined that the first temperature sensor 4 is short-circuited.

[0051] Following the system power-on procedure, an over-temperature detection step is also included, which includes: Step S13: When the first temperature sensor 4 detects that the current temperature exceeds 45°C, the power supply to the heating element 2 is immediately disconnected.

[0052] The milk was heated using the appliance anti-dry-burning protection method of this embodiment. The temperature of the milk was measured during the warming process, and the results are shown in Table 1. The milk was eventually able to stabilize within the set temperature range. Figure 2 The data graph shows the process of heating 240ml of milk using the appliance anti-dry-burning protection method of the present invention. Figure 3 The data graph shows the process of heating 120ml of milk using the appliance anti-dry-burning protection method of the present invention.

[0053]

[0054] Table 1 In this embodiment, by first adopting a multi-stage heating method, after each stage of heating, the slope of the heating curve is calculated, and it is determined whether the container 1 is dry-burning. This method is not easily affected by the surrounding heat source, has a high accuracy rate, and the detection time interval between each stage is short and the response is fast, ensuring the safety of the appliance while rapidly heating the liquid. It is especially suitable for heating liquid beverages.

[0055] Second embodiment: This embodiment discloses a system for implementing the home appliance anti-dry-burning protection method of the first embodiment.

[0056] Figure 4 This is a structural diagram of the system of the present invention. Figure 5 This is a connection diagram of the system of the present invention. For example... Figure 4 and Figure 5 As shown, the system includes a container body 1, a heating element 2 disposed at the bottom inner side of the container body 1, a first temperature sensor 4 embedded at the upper end of the heating element 2, and a heat insulation plate 3 disposed between the heating element 2 and the first temperature sensor 4. The system also includes a controller 7, which is electrically connected to the heating element 2 and the first temperature sensor 4.

[0057] For example, the container body 1 is made of metal, preferably stainless steel, and the PWM duty cycle and heating time are adjusted accordingly based on the material. The controller 7 can be a commercially available PLC controller 7. The first temperature sensor 4 is an NTC temperature sensor. The heating element 2 is made of PTC ceramic with a Curie point temperature of 120°C. Above this temperature, the resistance increases sharply, and the power automatically drops to an extremely low level.

[0058] Furthermore, a second temperature sensor 5 is provided at the lower end of the heating element 2. The second temperature sensor 5 is a mechanical temperature sensor with a trigger temperature of 120°C. When the temperature reaches 120°C, the bimetallic strip activates, physically disconnecting the main circuit. In other embodiments of the present invention, the second temperature sensor 5 may also be a fuse or a manually reset temperature limiter, etc., as long as it can generate mechanical action and disconnect the circuit according to temperature changes. The present invention does not impose further limitations on this.

[0059] A third temperature sensor 6 is installed on the outside of the container body 1. The third temperature sensor 6 detects the ambient temperature and is electrically connected to the controller 7.

[0060] In this embodiment, a triple overheat protection system is adopted. The first layer is that the heating element 2 uses the self-limiting temperature physical property of PTC ceramic, which automatically reduces power when the temperature exceeds the limit. The second layer is that the first temperature sensor 4 collects the temperature, and disconnects the power supply to the heating element 2 when the temperature exceeds the limit. The third layer is that the mechanical temperature sensor at the bottom of the heating element 2 triggers a mechanical action to disconnect the circuit when the temperature exceeds the limit. By setting up a triple overheat protection system, it is ensured that the failure of any single component will not affect the normal operation of the system, resulting in high safety and reliability.

[0061] It should be noted that the steps described in this manual do not necessarily have a strict sequential order. Without affecting the implementation of the relevant functions, the steps can be adjusted, combined, or split according to actual needs, and some steps can be selected for execution based on the specific application scenario; steps that can be executed in parallel can also be executed simultaneously or alternately. Unless otherwise explicitly specified, the numbering or order of the steps should not be construed as a limitation on the order of execution.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for protecting household appliances from dry burning, characterized in that, The method for preventing dry burning of household appliances includes the following steps: System power-on; The first temperature sensor acquires the initial temperature T0 of the liquid inside the container, and compares the initial temperature T0 with the preset temperature T. 预设 Compare; If T0 < T 预设 Heating the liquid inside the container using a multi-stage heating mode includes the following steps: The heating element heats up at the set maximum PWM duty cycle value; At preset intervals, the first temperature sensor collects the temperature of the liquid inside the container and calculates the slope of the heating curve. If the slope of the heating curve is within the preset range, then reduce the PWM duty cycle value of the heating element; If the slope of the heating curve is greater than the preset range, it is determined that the container is dry-burning and the heating element is de-energized.

2. The method for preventing dry burning of household appliances according to claim 1, characterized in that, The steps for heating the liquid inside the container using a multi-stage heating mode include: First stage heating: Heating is performed using the first PWM duty cycle value. At intervals of t1, the first temperature sensor collects the temperature T1 and calculates the temperature rise slope k1 from T0 to T1. If k1 ≥ 0.4, it is determined that the container is dry-burning, and the heating element is powered off. If 0.4 > k1 ≥ 0.2, it is determined that the water content in the container is low, and the process jumps to the third stage heating. If k1 < 0.2, it is determined that the water content in the container is high, and the process jumps to the second stage heating. Second stage heating: Heating is performed with the second PWM duty cycle value. At intervals of t2, the first temperature sensor collects the temperature T2 and calculates the temperature rise slope k2 from T1 to T2. If 0.4 > k2 ≥ 0.2, it is determined that the water volume in the container is low, and the process jumps to the third stage heating. If k2 < 0.2, it is determined that the water volume in the container is high, and the process jumps to the third stage heating. The third stage of heating: Heating is performed using the third PWM duty cycle. At intervals of t3, the first temperature sensor collects the temperature T3 and calculates the temperature rise slope k3 from T2 to T3. If k3 ≥ 0.4, it is determined that the container is dry-burning, and the heating element 2 is powered off. If 0.4 > k3 ≥ 0.2, it is determined that there is little water in the container, and the process jumps to the fourth stage of heating. If k3 < 0.2, it is determined that there is a lot of water in container 1, and the process jumps to the fourth stage of heating. Fourth stage heating: Heating is performed with the fourth PWM duty cycle value. At an interval of t4, the first temperature sensor collects the temperature T4 and calculates the temperature rise slope k4 from T3 to T4. If k4≥0.4, it is determined that the container is dry-burning and the heating element is powered off. If k4<0.4, it is determined that the water volume in the container is normal and it switches to the constant temperature heat preservation mode to heat the liquid in the container. Among them, the duty cycle values ​​of the first PWM, the second PWM, the third PWM, and the fourth PWM decrease sequentially.

3. The method for preventing dry burning of household appliances according to claim 2, characterized in that: The first PWM duty cycle is 100%, and the heating time is 60 seconds; the second PWM duty cycle is 80%, and the heating time is 120 seconds; the third PWM duty cycle is 50%, and the heating time is 120 seconds; the fourth PWM duty cycle is 30%, and the heating time is 60 seconds.

4. The method for preventing dry burning of household appliances according to claim 1, characterized in that: If T0 < T 预设 After the step of heating the liquid inside the container using a multi-stage heating mode, the process also includes the following steps: Until the PWM duty cycle value of the heating element drops to the set minimum value, it switches to constant temperature heat preservation mode to heat the liquid in the container. If T0≥T 预设 When the PWM duty cycle of the heating element drops to the set minimum value, the liquid in the container is heated in a constant temperature insulation mode. Heating the liquid inside the container using a constant temperature insulation mode includes the following steps: The heating element heats at the set minimum PWM duty cycle value; The first temperature sensor collects the current temperature T in real time. 当前 ; If T 当前 ≥T 预设 If this happens, the heating element will stop heating; If T 当前 <T 预设范围 If this occurs, the heating element will restart.

5. The method for preventing dry burning of household appliances according to claim 1, characterized in that: The formula for calculating the slope of the heating curve is: k= ; Among them, T 上一时刻 The temperature last collected by the first temperature sensor. t is the time interval between two temperature acquisitions.

6. The method for preventing dry burning of household appliances according to claim 1, characterized in that: If the slope of the heating curve is greater than the preset range, the steps to determine if the container is dry-burning include: When the first temperature sensor detects that the slope of the temperature rise curve is greater than the preset range for the first time, the system marks it as "suspected dry burning state" and repeats the calculation of the slope of the temperature rise curve in the next three acquisition cycles; only when the slope of the temperature rise curve is greater than the preset range for three consecutive times is it determined that the container is dry burning and the heating element is powered off.

7. The method for preventing dry burning of household appliances according to claim 1, characterized in that: Following the system power-on procedure, the following steps are also included: The third temperature sensor collects the ambient temperature T. env The dry-burning threshold k is dynamically adjusted, and the dry-burning threshold k satisfies the following formula: k=1.0-0.01×(25℃-T env )。 8. The method for preventing dry burning of household appliances according to claim 1, characterized in that: Following the system power-on procedure, a failure detection procedure is also included, which includes: The resistance value across the first temperature sensor is detected. If it is within the set value range, it is considered normal. If it is greater than the set value, it is considered that the first temperature sensor is open-circuited. If it is less than the set value, it is considered that the first temperature sensor is short-circuited. After determining that the container body is dry-burning, the process also includes a heating element abnormal conduction detection step, which includes: If the first temperature sensor detects that the current temperature is still rising by more than 3°C / min after the heating element is powered off, the system power supply will be immediately disconnected. After the system power-on procedure, an over-temperature detection procedure is also included. The over-temperature detection procedure includes: When the first temperature sensor detects that the current temperature exceeds 45°C, the power supply to the heating element is immediately disconnected.

9. A system for implementing the household appliance anti-dry-burning protection method according to any one of claims 1 to 8, characterized in that: The system includes a container body, a heating element is disposed at the bottom inside the container body, a first temperature sensor is embedded at the upper end of the heating element, and a heat insulation plate is disposed between the heating element and the first temperature sensor; the system also includes a controller, which is electrically connected to the heating element and the first temperature sensor.

10. The system according to claim 9, characterized in that: A second temperature sensor is provided at the lower end of the heating element. The second temperature sensor is a mechanical temperature sensor with a trigger temperature of 120°C. The first temperature sensor is an NTC temperature sensor. The heating element is made of PTC ceramic with a Curie point temperature of 120°C.

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