Automatic pot overflow prevention control method of induction cooker, storage medium and induction cooker

Abstract

The invention relates to the technical field of kitchen equipment, and particularly discloses an automatic spill-proof control method for an induction cooker, a storage medium and the induction cooker, and the method comprises the following steps: monitoring the temperature of a pot bottom in real time through a temperature sensor, and calculating a temperature rise slope (T) every 6 seconds by an MCU; when the temperature reaches a preset threshold value and T drops from a peak value, it is judged that water is about to boil, and heating power is reduced in a graded mode. According to the method, the temperature rise rate change characteristic (acceleration and deceleration after 70 DEG C) caused by bubbles before water boiling is creatively utilized, the boiling trend is pre-judged through an algorithm, and beforehand prevention is achieved. Compared with a traditional lag response scheme, the method has the advantages that on the premise that hardware cost is not increased, the accuracy and reliability of anti-overflow control are remarkably improved, and the problem of response delay is solved. The core principle is to capture a'temperature rise-speed reduction 'inflection point caused by bubble generation and realize intelligent firepower adjustment through a software algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen equipment, and in particular to an automatic anti-overflow pot control method for an induction cooker, a storage medium, and an induction cooker. Background Art

[0002] Currently, induction cookers on the market primarily implement overflow prevention through liquid contact detection, fixed temperature threshold power-off, or mechanical overflow prevention. However, these solutions all have significant flaws: liquid detection methods are slow to respond and prone to false triggering, temperature threshold methods cannot adapt to boiling point fluctuations caused by varying altitudes and cookware, and mechanical designs only address the symptoms rather than the root cause. The root cause of these issues lies in the passive response mechanisms of existing technologies, which rely on post-overflow detection or fixed boiling point determination, lacking the ability to predict boiling trends. Furthermore, the additional hardware modules not only increase costs but also pose a risk of electric shock, while the crude "full power-off" switching method can lead to drastic temperature fluctuations. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems that the existing induction cooker adopts a passive response mechanism, lacks the ability to predict boiling trends and is high in cost.

[0004] In order to achieve the above invention objectives, the present invention adopts the following technical solutions:

[0005] An automatic anti-overflow control method for an induction cooker includes the following steps: presetting a sampling period, a starting temperature threshold, and a temperature slope critical value through an MCU module; detecting temperature changes at the bottom of the pot in real time through a temperature sensor; the MCU module receiving the temperature signal and performing the following operations: recording the resistance and power values ​​corresponding to the temperature sensor at different working gears, calculating the temperature rise slope once per preset sampling period, and determining that the water is about to boil when the temperature reaches the preset starting temperature threshold and ΔT begins to decrease from a peak value, and controlling the heating module to reduce the heating power in stages according to the ΔT value.

[0006] The control method of the present invention uses a temperature sensor to monitor the temperature change at the bottom of the pot in real time. The MCU calculates the temperature rise slope (ΔT) every 6 seconds. When ΔT begins to decrease from its peak value, it determines that the water is about to boil and initiates multi-stage overflow prevention control. This method has the beneficial effect of shifting from "post-processing" to "pre-emptive prevention." By using a software algorithm to predict boiling trends in advance, it overcomes the response lag of traditional solutions while simultaneously increasing the accuracy and reliability of overflow prevention control without increasing hardware costs. The principle of the present invention is that water undergoes three stages of change during heating. Initially, the water temperature rises evenly. When the temperature exceeds 70°C, small bubbles begin to form at the bottom of the pot. These bubbles act like a "heat insulation pad," blocking some heat transfer and consuming energy to generate bubbles rather than heating the water. This causes the temperature rise to initially accelerate slightly before significantly slowing down. When the system detects a sustained decrease in the temperature rise (for example, a temperature increase of less than 1.5°C in 6 seconds), it predicts that the water is about to boil and automatically lowers the heat.

[0007] Furthermore, in the MCU module controlling the graded reduction of the heating power of the heating module according to the △T value, the heating power of the heating power is dynamically adjusted through the PWM duty cycle, and includes first-level power reduction, second-level power reduction and third-level power reduction steps, wherein the first-level power reduction includes reducing the heating power by 35% when △T drops for the first time; the second-level power reduction includes continuing to reduce the heating power when △T drops for two consecutive times, so that the heating module switches to the intermittent heating mode; the third-level power reduction includes further reducing the duty cycle to ≤30% when the △T change value is less than the temperature slope critical value, and entering the slow fire insulation mode.

[0008] Furthermore, the duty cycle of the intermittent heating mode is dynamically adjusted according to the size of the pot and the liquid volume. The larger the pot size, the lower the amplitude of the dynamic adjustment, and vice versa.

[0009] Furthermore, the detection range of the temperature sensor is 0-100°C, and the analog signal output by the temperature sensor is quantized by an ADC converter to generate a digital output code; the number of bits of the ADC converter is a; the adjacent sampling difference of the digital output code obtained by the MCU is set to △AD, and when △AD is less than a critical AD difference c, it is determined that the temperature change is less than a temperature slope critical value P; the critical AD difference c is determined by the following formula: c = [(P × 2 a) / 100], where a is the number of bits in the ADC converter. The advantage of this solution lies in its automatic adaptation to any ADC's bit count through dynamic algorithmic calculation, eliminating the need for specific ADC converter models or bit counts, significantly enhancing the solution's versatility and hardware compatibility. This design not only flexibly accommodates varying temperature slope thresholds (P), simply adjusting parameters to meet the induction cooker's accuracy requirements, but also ensures the accuracy of the calculation results through mathematical quantization, avoiding errors in empirically derived values. When replacing a high-precision ADC or modifying the temperature threshold, the system automatically generates a new critical ADC difference (c), eliminating the need to redesign the threshold. For example, whether the induction cooker uses a 10-bit ADC (c = 20 when P = 2°C) or a 12-bit ADC (c = 20 when P = 0.5°C), the system automatically calculates the correct critical difference.

[0010] Preferably, the detection range of the temperature sensor is 0-100°C, the temperature slope critical value is 1.5°C, the analog signal output by the temperature sensor is quantized by the ADC converter to generate a digital output code, and the ADC converter has an 8-bit resolution; the adjacent sampling difference of the digital output code obtained by the MCU is set to △AD, and when △AD is less than 3 ADs, it is judged to be less than the temperature slope critical value. In this solution, the MCU calculates the △AD value (corresponding to △T) of adjacent sampling periods by difference, and triggers the boiling prediction algorithm when it detects that △AD continuously decreases and the cumulative change is greater than 3 AD values. This algorithm is based on the physical property that the heat conduction efficiency decreases when the liquid changes phase. Compared with traditional timing or threshold control, the slope algorithm can identify the unique thermodynamic characteristics of the initial boiling stage and achieve early warning. The principle of this solution is: Since the effective detection range of the temperature sensor is 0-100℃, the 8-bit ADC converter can convert 0-100℃ into a digital value of 0-255. Therefore, each AD value of the 8-bit ADC converter corresponds to a temperature value of approximately 0.4℃, 3 AD values ​​are approximately 1.2℃, and 4 AD values ​​are greater than 1.5℃. Therefore, when △AD is less than 3 AD values, it is determined that the temperature change is less than the temperature slope critical value, and the heating power of the heating module can be adjusted in time to avoid water overflow.

[0011] Furthermore, the temperature sensor includes a non-contact temperature sensor.

[0012] Furthermore, the temperature sensor includes an NTC thermistor and a fixed circuit. The NTC thermistor and the fixed resistor form a voltage divider circuit, the output of which is connected to the analog input channel of an ADC converter. This solution uses the NTC thermistor voltage divider circuit to convert temperature changes into a voltage signal, achieving a quantization accuracy of 0.4°C / AD value using an 8-bit ADC. The voltage divider circuit design ensures linearity over a 100°C range.

[0013] Furthermore, the preset sampling period is 6 seconds, and the starting temperature threshold is 70°C.

[0014] A second object of the present invention is to provide a storage medium having a control program thereon, wherein the control program executes the control method according to the above method when started.

[0015] The third invention object of the present invention is to provide an induction cooker, which is provided with a control circuit, and the control circuit includes an MCU module, a temperature sensor, a heating module, an ADC converter, and the storage medium according to claim 8. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flowchart of the method of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below with reference to the accompanying drawings:

[0018] In the description of the present invention, it should be understood that the orientations or positional relationships indicated by “up”, “down”, “left”, “right”, “horizontal”, “inside”, “outside”, etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] See also Figure 1 As shown, the present invention discloses an automatic anti-overflow pot control method for an induction cooker, comprising the following steps: (1) initializing parameters: presetting a sampling period, a starting temperature threshold, and a temperature slope critical value through an MCU module; (2) real-time temperature detection: detecting the temperature change of the bottom of the pot in real time through a temperature sensor; (3) calculating the temperature change slope and judging the boiling trend, and reducing the power in stages to prevent overflow: the MCU module receives the temperature signal and performs the following operations: recording the resistance value and power value corresponding to the temperature sensor under different working gears, calculating the temperature rising slope once per preset sampling period, and when the temperature reaches the preset starting temperature threshold and ΔT starts to decrease from the peak value, determining that the water is about to boil and controlling the heating module to reduce the heating power in stages according to the ΔT value.

[0020] In the MCU module controlling the graded reduction of the heating power of the heating module according to the ΔT value, the heating power of the heating power is dynamically adjusted through the PWM duty cycle, and includes first-level power reduction, second-level power reduction and third-level power reduction steps, wherein the first-level power reduction includes reducing the heating power by 35% when ΔT drops for the first time; the second-level power reduction includes continuing to reduce the heating power when ΔT drops for two consecutive times, so that the heating module switches to the intermittent heating mode; the third-level power reduction includes further reducing the duty cycle to ≤30% when the ΔT change value is less than the temperature slope critical value, and entering the slow fire insulation mode.

[0021] Furthermore, the duty cycle of the intermittent heating mode is dynamically adjusted according to the size of the pot and the liquid capacity.

[0022] The detection range of the temperature sensor is 0-100°C. The analog signal output by the temperature sensor is quantized by an ADC converter to generate a digital output code. The number of bits of the ADC converter is a, and the digital value range of the output is 0 to 2^a-1. The difference between adjacent samples of the digital output code obtained by the MCU is set to △AD. When △AD is less than the critical ADC difference c, it is determined that the temperature change is less than the temperature slope critical value P. The critical ADC difference c is determined by the following formula: c = [(P × 2 a ) / 100], where a is the number of bits of the ADC converter.

[0023] The specific principle of the above scheme is: after the analog signal output by the temperature sensor is converted by ADC, the temperature change slope △T is converted into the adjacent sampling difference △AD of the digital quantity. Since the ADC bit a directly affects the temperature resolution (each AD value corresponds to 100 / 2 a , unit is °C), the critical AD difference c needs to be dynamically adapted to the ADC accuracy.

[0024] The derivation logic of the formula is:

[0025] Numerator P*2a: maps the temperature slope critical value P to the digital value range;

[0026] Denominator 100: normalized to the sensor range;

[0027] Rounding operation: Ensure that c is an integer AD value.

[0028] Preferably, the ADC converter has an 8-bit resolution. The difference between adjacent samples of the digital output code obtained by the MCU is set to ΔAD. When ΔAD is less than 3 AD values, it is determined to be less than the temperature slope threshold. In this solution, the MCU calculates the ΔAD values ​​(corresponding to ΔT) of adjacent sampling periods by differential calculation. When it detects a continuous decrease in ΔAD with a cumulative change greater than 3 AD values, it triggers a boiling prediction algorithm. This algorithm is based on the physical property that heat conduction efficiency decreases during liquid phase change. Compared to traditional timing or threshold control, the slope algorithm can identify the unique thermodynamic characteristics of the early stages of boiling, providing early warning. The principle of this solution is that since the effective detection range of the temperature sensor is 0-100°C, the 8-bit ADC converter can convert 0-100°C into a digital value of 0-255. Therefore, each AD value of the 8-bit ADC converter corresponds to a temperature value of approximately 0.4°C, 3 AD values ​​are approximately 1.2°C, and 4 AD values ​​are greater than 1.5°C. Therefore, when ΔAD is less than 3 AD values, the temperature change is determined to be less than the temperature slope threshold, and the heating power of the heating module can be adjusted in a timely manner to prevent water overflow.

[0029] The temperature sensor mentioned above is a non-contact temperature sensor.

[0030] The temperature sensor consists of an NTC thermistor and a fixed circuit. The NTC thermistor and the fixed resistor form a voltage divider circuit, the output of which is connected to the analog input channel of an ADC converter. This solution uses the NTC thermistor voltage divider circuit to convert temperature changes into a voltage signal, achieving a quantization accuracy of 0.4°C / AD value using an 8-bit ADC. The voltage divider circuit design ensures linearity over a 100°C range.

[0031] The preset sampling period is 6 seconds, and the starting temperature threshold is 70°C.

[0032] The control method of the present invention uses a temperature sensor to monitor the temperature change at the bottom of the pot in real time. The MCU calculates the temperature rise slope (ΔT) every 6 seconds. When ΔT begins to decrease from its peak value, it determines that the water is about to boil and initiates multi-stage overflow prevention control. This method has the beneficial effect of shifting from "post-processing" to "pre-emptive prevention." By using an algorithm to predict boiling trends in advance, it overcomes the response lag problem of traditional solutions while simultaneously increasing the accuracy and reliability of overflow prevention control without increasing hardware costs. The principle of the present invention is that water undergoes three stages of change during heating. Initially, the water temperature rises evenly. When the temperature exceeds 70°C, small bubbles begin to form at the bottom of the pot. These bubbles act like a "heat insulation pad," blocking some heat transfer and consuming energy to generate bubbles rather than heating the water. This causes the temperature rise rate to initially accelerate slightly before significantly slowing down. When the system detects a sustained decrease in the temperature rise rate (for example, a temperature increase of less than 1.5°C in 6 seconds), it predicts that the water is about to boil and automatically lowers the heat.

[0033] The present invention also discloses a storage medium. A control program is provided on the storage medium. When the control program is started, the control method according to the above method is executed.

[0034] The present invention also discloses an induction cooker, which is provided with a control circuit. The control circuit includes an MCU module, a temperature sensor, a heating module, an ADC converter, and the storage medium according to claim 8.

[0035] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other. According to the disclosure and teachings of the above description, those skilled in the art to which the present invention belongs can also change and modify the above-mentioned embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. An automatic anti-overflow control method for an induction cooker, characterized by: The following steps are involved: The sampling period, startup temperature threshold and temperature slope critical value P are preset through the MCU module; The temperature change of the bottom of the pot is detected in real time through the temperature sensor; The MCU module receives the temperature signal and performs the following operations: recording the resistance and power values ​​corresponding to the temperature sensor at different working levels, calculating the temperature rise slope △T once every preset sampling period, and when the temperature reaches the preset start temperature threshold and △T starts to decrease from the peak value, controlling the heating module to reduce the heating power in stages according to the △T value.

2. The control method according to claim 1, wherein: In the process where the MCU module controls the heating module to reduce the heating power in stages according to the ΔT value, the heating power is dynamically adjusted by the PWM duty cycle, and the process includes the following steps: First level power reduction: when △T decreases for the first time, the heating power is reduced by 35%; Second level power reduction: when △T decreases twice in succession, the heating power will continue to be reduced, and the heating module will switch to intermittent heating mode; The third level of power reduction is when the △T change value is less than the temperature slope critical value P, the duty cycle is further reduced to ≤30%, and the system enters the slow fire keeping mode.

3. The control method according to claim 2, wherein: The duty cycle of the intermittent heating mode is dynamically adjusted according to the size of the pot and the liquid capacity.

4. The control method according to claim 2, wherein: The detection range of the temperature sensor is 0-100°C, and the analog signal output by the temperature sensor is quantized by an ADC converter to generate a digital output code. The number of bits of the ADC converter is a; The adjacent sampling difference of the digital output code obtained by the MCU is set to △AD. When △AD is less than the critical AD difference c, it is determined that the temperature change is less than the temperature slope critical value P; The critical AD difference c is determined by the following formula: c=[(P×2 a ) / 100] Where a is the number of bits of the ADC converter.

5. The control method according to claim 2, wherein: The analog signal output by the temperature sensor is quantized by the ADC converter to generate a digital output code, and the ADC converter has an 8-bit resolution. When ΔAD < 3 AD The temperature slope critical value is 1.5°C, the analog signal output by the temperature sensor is quantized by an ADC converter to generate a digital output code, and the ADC converter has an 8-bit resolution; The adjacent sampling difference of the digital output code obtained by the MCU is set to △AD. When △AD is less than 3 ADs, it is determined to be less than the temperature slope critical value.

6. The control method according to claim 2, wherein: The temperature sensor may be a non-contact temperature sensor.

7. The control method according to claim 2, characterized in that: The temperature sensor includes an NTC thermistor and a fixed circuit. The NTC thermistor and the fixed resistor form a voltage divider circuit. The output end of the voltage divider circuit is connected to an analog input channel of an ADC converter.

8. The control method according to claim 2, wherein: The preset sampling period is 6 seconds, and the starting temperature threshold is 70°C.

9. A storage medium, characterized in that: The storage medium is provided with a control program, and when the control program is started, the control method according to any one of claims 1 to 8 is executed.

10. Induction cooker, characterized by: The induction cooker is provided with a control circuit, which includes an MCU module, a temperature sensor, a heating module, an ADC converter, and the storage medium according to claim 9.

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