Constant temperature heating control method based on power and temperature double closed loop of induction cooker

Abstract

The present invention discloses a constant temperature heating control method based on the power and temperature double closed loop of an induction cooker: comprising the following steps: S1: preset working temperature value; S2: read the actual temperature of the induction cooker panel; S3: the central processing unit determines whether the actual temperature of the induction cooker panel is greater than the preset working temperature value; S4: read the current input voltage of the induction cooker, and transmit the read voltage value to the central processing unit. The constant temperature heating control method based on the power and temperature double closed loop of an induction cooker proposed by the present invention realizes temperature control of the bottom of a pot, repeats multiple cycles of heating power adjustment and temperature feedback, continuously adjusts the temperature, makes the temperature tend to the preset temperature value, until the temperature stabilizes at the preset temperature value, and realizes precise constant temperature heating of the bottom of the pot.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic oven temperature control, and in particular to a constant temperature heating control method based on a power and temperature double closed loop of an electromagnetic oven. Background Art

[0002] The temperature of a cooking pot varies due to the heating source, while the constant heating temperature of the bottom of the pot is very important for the taste and quality of the cooked food. However, most of the induction cookers on the market lack the function of precise heating and temperature control. In order to achieve the purpose of precise heating and constant temperature, a constant temperature heating control method based on the power and temperature double closed loop of the induction cooker is proposed. Summary of the invention

[0003] The purpose of the present invention is to provide a constant temperature heating control method based on the power and temperature double closed loop of an induction cooker, which can adjust the heating temperature of the bottom of the pot to a constant state and realize precise constant temperature heating of the bottom of the pot, so as to solve the problem that constant temperature heating of the bottom of the pot cannot be achieved in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a constant temperature heating control method based on the power and temperature double closed loop of an induction cooker, comprising the following steps:

[0005] S1: preset working temperature value;

[0006] S2: Read the actual temperature of the induction cooker panel and transmit the read temperature signal to the central processor;

[0007] S3: The central processing unit determines whether the actual temperature of the induction cooker panel is greater than the preset working temperature value;

[0008] S4: Read the current input voltage of the induction cooker and transmit the read voltage value to the central processor;

[0009] S5: read the current input current of the induction cooker and transmit the read voltage value to the central processor;

[0010] S6: The algorithm built into the CPU calculates the current input power, which is the voltage value read in S4 multiplied by the current value read in S5, using the following formula: P = UI;

[0011] S7: The central processor determines whether the input power is greater than the set input power:

[0012] Preferably, the temperature of the induction cooker panel is read using a temperature sampling circuit, which includes a pin header CN1, a resistor R23, a resistor R26, a temperature sensor resistor Rz, a capacitor C11 and a TMAIN signal output terminal. The temperature sensor resistor Rz is attached to the induction cooker panel, the input end of the temperature sensor resistor Rz is connected to pin 3 of the pin header CN1, the output end of the temperature sensor resistor Rz is connected to pin 4 of the pin header CN1, pin 1 of the pin header CN1 is connected to the input end of the resistor R26, and connected to the output end of the resistor R23, the input end of the resistor R23 is connected to the +5V power supply terminal, the output end of the resistor R26 is connected to the output of the TMAIN signal output terminal, and connected to the input end of the capacitor C11, the output end of the capacitor C11 is connected to pin 2 of the pin header CN1 and then grounded, and a 12-bit AD sampling module is used to obtain the AD value formula of Tad=4096*Rz / (Rz+2). According to the above formula, and then compared with the relationship table between resistance and temperature in the specification of Rz, the current temperature value can be accurately known.

[0013] Preferably, the output voltage of the induction cooker is sampled before the input voltage of the induction cooker is read. The voltage sampling adopts a voltage sampling circuit. The voltage sampling circuit includes resistor R35, resistor R36, resistor R38, resistor R48, resistor R43, capacitor C19 and capacitor C20. The input end of resistor R35 is connected in parallel to the busbar of the power input end of the induction cooker, the output end of resistor R35 is electrically connected to the input end of resistor R36, the output end of resistor R36 is electrically connected to the input end of resistor R38, the output end of resistor R38 is connected to the input end of resistor R48, and is connected to the input end of resistor R43 and the input end of capacitor C20. The output end of resistor R48 and the output end of capacitor C20 are both grounded, the output end of resistor R43 is connected to the AD-Vin power signal terminal output, and is connected to the input end of capacitor C19, and the output end of capacitor C19 is grounded.

[0014] Preferably, the output current of the induction cooker is sampled before the input current of the induction cooker is read. The current sampling adopts a current sampling circuit, which includes an operational amplifier IC6, a resistor R42, a resistor R48, a capacitor C40, a resistor R49, a resistor R45 and a capacitor C16. The positive electrode of the operational amplifier IC6 is connected to the output end of the resistor R42 and to the input end of the capacitor C29. The input end of the resistor R42 is connected in series to the bus bar of the induction cooker power input end. The negative electrode of the operational amplifier IC6 is connected to the output end of the capacitor C29 and to the input end of the resistor R48. The output end of the resistor R48 is grounded; the negative electrode of the operational amplifier IC6 is connected to the input end of the capacitor C40 and to the input end of the resistor R49. The output end of the capacitor C40 is connected to the output end of the resistor R49 and then to the output end of the operational amplifier IC6. The output end of the operational amplifier IC6 is connected to the input end of the resistor R45. The output end of the resistor R45 is connected to the Curreng-V signal terminal output and to the input end of the capacitor C16. The output end of the capacitor C16 is grounded.

[0015] Preferably, the central processing unit has a built-in main control circuit, which includes a chip U1. The model of chip U1 is PIC16F. Chip U1 has a built-in comparator and an external PID algorithm. The PID algorithm is an algorithm based on FPGS. Pin 1 of chip U1 is connected to the TMAIN signal output terminal, pin 44 of chip U1 is connected to the AD-Vin power supply signal terminal, and pin 42 of chip U1 is connected to the Curreng-V signal terminal.

[0016] Preferably, the output end of the induction cooker is connected to an IGBT driving circuit, the source of the IGBT end of the IGBT driving circuit is connected to pin 10 of the chip U1, the gate of the IGBT end is connected to the power input, the drain of the IGBT end is connected to the input end of the diode D8, and the output end of the diode D8 is connected to the source of the IGBT end and then connected to the power output terminal to supply power to the working end of the induction cooker.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the constant temperature heating control method based on the power and temperature double closed loop of the induction cooker proposed by the present invention, through the preset temperature value, the temperature sampling circuit collects the real-time temperature of the induction cooker panel, and transmits the temperature signal to the central processing unit, the central processing unit compares the received temperature value with the preset temperature value to obtain a difference, and brings the difference into the built-in PID algorithm of the central processing unit for calculation, and the obtained data is used as the actual power setting value, and the current value detected by the current detection circuit and the voltage value sampled by the voltage sampling circuit are multiplied to obtain a power value, which is recorded as the actual power value, and the set power Subtract the actual power value from the error value Err1, substitute Err1 into the formula: Output1=Kp1*Err1+∑Ki1*Err1, calculate the Output1 value, use the calculated Output1 value as the heating power output parameter, and use the heating power output parameter to proportionally reduce the heating power of the IGBT, so as to reduce the temperature of the pot bottom and control the temperature of the pot bottom. Repeat multiple cycles of heating power adjustment and temperature feedback, and continuously adjust the temperature to make the temperature approach the preset temperature value until the temperature stabilizes at the preset temperature value. The overall heating temperature of the pot bottom can be adjusted to a constant state, so as to achieve precise constant temperature heating of the pot bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a constant temperature control flow chart of the present invention;

[0019] Figure 2 It is a block diagram of the working principle of the present invention;

[0020] Figure 3 It is the temperature sampling circuit diagram of the present invention;

[0021] Figure 4 It is a voltage sampling circuit diagram of the present invention;

[0022] Figure 5 is a current sampling circuit diagram of the present invention;

[0023] Figure 6 The IGBT driving circuit diagram of the present invention;

[0024] Figure 7 It is a control circuit diagram of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1-2 The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker includes the following steps:

[0027] Step 1: preset the working temperature value;

[0028] Step 2: Read the actual temperature of the induction cooker panel and transmit the read temperature signal to the central processor;

[0029] Step 3: The central processing unit determines whether the actual temperature of the induction cooker panel is greater than the preset working temperature value. Greater than the preset working temperature value: by PID algorithm, subtract the set output power.

[0030] Less than the preset operating temperature value: The PID algorithm increases the set output power, and the power determines the temperature of the induction cooker panel.

[0031] Step 4: Read the current input voltage of the induction cooker and transmit the read voltage value to the central processor;

[0032] Step 5: Read the current input current of the induction cooker and transmit the read voltage value to the central processor;

[0033] Step 6: The algorithm built into the CPU calculates the current input power, which is the voltage value read in S4 multiplied by the current value read in S5, and the formula is as follows: P = UI;

[0034] Step 7: The CPU determines whether the input power is greater than the set input power

[0035] Greater than input power: PID algorithm reduces the operating opening of the induction cooker.

[0036] Less than input power: The PID algorithm increases the opening of the induction cooker, and the size of the opening determines the current input power.

[0037] See also Figure 3 The temperature of the induction cooker panel is read using a temperature sampling circuit. The temperature sampling circuit includes a pin header CN1, a resistor R23, a resistor R26, a temperature sensor resistor Rz, a capacitor C11 and a TMAIN signal output terminal. The temperature sensor resistor Rz is attached to the induction cooker panel. The input end of the temperature sensor resistor Rz is connected to pin 3 of the pin header CN1, and the output end of the temperature sensor resistor Rz is connected to pin 4 of the pin header CN1. Pin 1 of the pin header CN1 is connected to the input end of the resistor R26 and to the output end of the resistor R23. The input end of the resistor R23 is connected to the +5V power supply terminal for power supply. The output end of the resistor R26 is connected to the TMAIN signal output terminal output and to the input end of the capacitor C11. The output end of the capacitor C11 is connected to pin 2 of the pin header CN1 and then grounded.

[0038] See also Figure 4 Before reading the input voltage of the induction cooker, the output voltage of the induction cooker is sampled. The voltage sampling adopts a voltage sampling circuit. The voltage sampling circuit includes a resistor R35, a resistor R36, a resistor R38, a resistor R48, a resistor R43, a capacitor C19 and a capacitor C20. The input end of the resistor R35 is connected in parallel to the busbar of the induction cooker power input end, the output end of the resistor R35 is electrically connected to the input end of the resistor R36, the output end of the resistor R36 is electrically connected to the input end of the resistor R38, the output end of the resistor R38 is connected to the input end of the resistor R48, and is connected to the input end of the resistor R43 and the input end of the capacitor C20. The output end of the resistor R48 and the output end of the capacitor C20 are both grounded, the output end of the resistor R43 is connected to the AD-Vin power signal terminal output, and is connected to the input end of the capacitor C19, and the output end of the capacitor C19 is grounded.

[0039] See also Figure 5 Before reading the input current of the induction cooker, the output current of the induction cooker is sampled. The current sampling adopts a current sampling circuit. The current sampling circuit includes an operational amplifier IC6, a resistor R42, a resistor R48, a capacitor C40, a resistor R49, a resistor R45 and a capacitor C16. The positive electrode of the operational amplifier IC6 is connected to the output end of the resistor R42 and to the input end of the capacitor C29. The input end of the resistor R42 is connected in series to the bus bar of the induction cooker power input end. The negative electrode of the operational amplifier IC6 is connected to the output end of the capacitor C29 and to the input end of the resistor R48. The output end of the resistor R48 is grounded; the negative electrode of the operational amplifier IC6 is connected to the input end of the capacitor C40 and to the input end of the resistor R49. The output end of the capacitor C40 is connected to the output end of the resistor R49 and then connected to the output end of the operational amplifier IC6. The output end of the operational amplifier IC6 is connected to the input end of the resistor R45. The output end of the resistor R45 is connected to the Curreng-V signal terminal output and to the input end of the capacitor C16. The output end of the capacitor C16 is grounded.

[0040] See also Figure 7 The central processing unit has a built-in main control circuit, which includes a chip U1. The model of chip U1 is PIC16F. Chip U1 has a built-in comparator and an external PID algorithm. The PID algorithm is an algorithm based on FPGS. Pin 1 of chip U1 is connected to the TMAIN signal output terminal, pin 44 of chip U1 is connected to the AD-Vin power supply signal terminal, and pin 42 of chip U1 is connected to the Curreng-V signal terminal.

[0041] See also Figure 6The output end of the induction cooker is connected to an IGBT driving circuit, the source of the IGBT end of the IGBT driving circuit is connected to pin 10 of the chip U1, the gate of the IGBT end is connected to the power input, the drain of the IGBT end is connected to the input end of the diode D8, and the output end of the diode D8 is connected to the source of the IGBT end and then connected to the power output terminal to supply power to the working end of the induction cooker.

[0042] The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker is used as follows: for example, the current temperature of the induction cooker panel is 120 degrees, and it needs to be adjusted to 60 degrees for heat preservation, which requires the following process:

[0043] 1. The user presses the button of the induction cooker and sets the gear to 60 degrees.

[0044] 2. The temperature sensor resistor Rz detects the temperature signal and transmits the temperature signal to the chip U1 through the TMAIN signal output terminal to read the current temperature of the induction cooker panel.

[0045] 3. Chip U1 compares the read temperature value with the preset temperature value (i.e., 60 degrees set at the gear position), and determines that the detected temperature is higher than the set temperature.

[0046] 4. Subtract the detected temperature from the set temperature to obtain a negative error value Err.

[0047] 5. Substitute Err into the formula: Output = Kp*Err + ∑Ki*Err. Since Err is a negative number, the calculated Output must be smaller than the previous one. The calculated value is used as the setting value of the actual power.

[0048] 6. The voltage sampling circuit collects the input voltage signal, and the current sampling circuit collects the input current signal. Chip U1 reads the input current value and voltage value, and multiplies the obtained current value and voltage value to obtain the actual input power. The actual power obtained is higher than the set input power.

[0049] 7. Subtract the actual input power from the set input power to get a negative error value Err1. Substitute Err1 into the formula: Output1 = Kp1*Err1+∑Ki1*Err1. Because Err1 is a negative number, the calculated Output1 must be smaller than the previous one.

[0050] 8. Use the calculated Output1 value as the heating power output parameter, and use the heating power output parameter to proportionally reduce the heating power of the IGBT, thereby reducing the temperature of the bottom of the pot and achieving temperature control of the bottom of the pot.

[0051] 9. Repeat multiple cycles of heating power adjustment and temperature feedback, and continuously adjust the temperature so that the temperature tends to the preset temperature value until the temperature stabilizes at the preset temperature value.

[0052] 10. When chip U1 compares the read temperature value with the preset temperature value (i.e., 60 degrees set at the gear position), it determines that the detected temperature is lower than the set temperature, and subtracts the detected temperature from the set temperature to obtain a positive error value Err; Err is substituted into the formula: Output = Kp*Err+∑Ki*Err, because Err is a positive number, the calculated Output is definitely larger than the previous one, and the calculated value is used as the set value of the actual power; the obtained current value and voltage value are multiplied to obtain the actual input power, and the actual power obtained is higher than the set input power. The set input power is subtracted from the actual input power to obtain a negative error value Err1, and Err1 is substituted into the formula: Output1 = Kp1*Err1+∑Ki1*Err1, because Err1 is a positive number, the calculated Output1 is definitely larger than the previous one; the calculated Output1 value is used as the heating power output parameter, and the heating power output parameter is used to increase the heating power of the IGBT in proportion, thereby reducing the temperature of the bottom of the pot and controlling the temperature of the bottom of the pot.

[0053] In summary, the constant temperature heating control method based on the power and temperature double closed loop of the induction cooker proposed by the present invention presets the temperature value, and at the same time, the temperature sampling circuit collects the real-time temperature of the induction cooker panel, and transmits the temperature signal to the central processing unit, and the central processing unit compares the received temperature value with the preset temperature value to obtain a difference, and brings the difference into the built-in PID algorithm of the central processing unit for calculation, and the obtained data is used as the actual power setting value, and the current value detected by the current detection circuit and the voltage value sampled by the voltage sampling circuit are multiplied to obtain a power value, which is recorded as the actual power value, and the set power value minus the actual power An error value Err1 is obtained, and Err1 is substituted into the formula: Output1=Kp1*Err1+∑Ki1*Err1, and the Output1 value is calculated. The calculated Output1 value is used as the heating power output parameter, and the heating power output parameter is used to proportionally reduce the heating power of the IGBT, so as to reduce the temperature of the pot bottom and realize the temperature control of the pot bottom. Repeat multiple cycles of heating power adjustment and temperature feedback, and continuously adjust the temperature to make the temperature tend to the preset temperature value until the temperature stabilizes at the preset temperature value. The overall heating temperature of the pot bottom can be adjusted to a constant state, so as to realize precise constant temperature heating of the pot bottom.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A constant temperature heating control method based on the power and temperature double closed loop of an induction cooker, characterized in that: The steps include: S1: preset working temperature value; S2: Read the actual temperature of the induction cooker panel and transmit the read temperature signal to the central processor; S3: The central processing unit determines whether the actual temperature of the induction cooker panel is greater than the preset working temperature value; S4: Read the current input voltage of the induction cooker and transmit the read voltage value to the central processor; S5: read the current input current of the induction cooker and transmit the read voltage value to the central processor; S6: The algorithm built into the CPU calculates the current input power, which is the voltage value read in S4 multiplied by the current value read in S5, using the following formula: P=UI; S7: The central processing unit determines whether the input power is greater than the set input power.

2. The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker according to claim 1, characterized in that: The actual temperature of the induction cooker panel is read by a temperature sampling circuit, which comprises a pin row (CN1), a resistor (R23), a resistor (R26), a temperature sensor resistor (Rz), a capacitor (C11) and a TMAIN signal output terminal. The temperature sensor resistor (Rz) is attached to the induction cooker panel, the input end of the temperature sensor resistor (Rz) is connected to the pin (3) of the pin row (CN1), the output end of the temperature sensor resistor (Rz) is connected to the pin (4) of the pin row (CN1), the pin (1) of the pin row (CN1) is connected to the input end of the resistor (R26) and to the output end of the resistor (R23), the input end of the resistor (R23) is connected to a +5V power supply terminal, the output end of the resistor (R26) is connected to the TMAIN signal output terminal output and to the input end of the capacitor (C11), and the output end of the capacitor (C11) is connected to the pin (2) of the pin row (CN1) and then grounded.

3. The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker as claimed in claim 1, characterized in that: The induction cooker output voltage is sampled before the current input voltage of the induction cooker is read. The voltage sampling adopts a voltage sampling circuit. The voltage sampling circuit comprises a resistor (R35), a resistor (R36), a resistor (R38), a resistor (R48), a resistor (R43), a capacitor (C19) and a capacitor (C20). The input end of the resistor (R35) is connected in parallel to the busbar of the induction cooker power input end. The output end of the resistor (R35) is electrically connected to the input end of the resistor (R36). The output end of the resistor (R36) is electrically connected to the input end of the resistor (R38). The output end of the resistor (R38) is connected to the input end of the resistor (R48), and is connected to the input end of the resistor (R43) and the input end of the capacitor (C20). The output end of the resistor (R48) and the output end of the capacitor (C20) are both grounded. The output end of the resistor (R43) is connected to the AD-Vin power signal terminal output and is connected to the input end of the capacitor (C19). The output end of the capacitor (C19) is grounded.

4. The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker according to claim 1, characterized in that: The output current of the induction cooker is sampled before the current input current of the induction cooker is read. The current sampling adopts a current sampling circuit. The current sampling circuit includes an operational amplifier (IC6), a resistor (R42), a resistor (R48), a capacitor (C40), a resistor (R49), a resistor (R45) and a capacitor (C16). The positive electrode of the operational amplifier (IC6) is connected to the output end of the resistor (R42) and to the input end of the capacitor (C29). The input end of the resistor (R42) is connected in series to the busbar of the input end of the induction cooker power supply. The negative electrode of the operational amplifier (IC6) is connected to the output end of the capacitor (C29). The operational amplifier (IC6) is connected to the input end of the resistor (R48), and the output end of the resistor (R48) is grounded; the negative electrode of the operational amplifier (IC6) is connected to the input end of the capacitor (C40) and to the input end of the resistor (R49); the output end of the capacitor (C40) is connected to the output end of the resistor (R49) and then connected to the output end of the operational amplifier (IC6); the output end of the operational amplifier (IC6) is connected to the input end of the resistor (R45); the output end of the resistor (R45) is connected to the Curreng-V signal output and to the input end of the capacitor (C16); and the output end of the capacitor (C16) is grounded.

5. The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker according to claim 1, characterized in that: The central processing unit has a built-in main control circuit, the main control circuit includes a chip (U1), the model of the chip (U1) is PIC16F, the chip (U1) has a built-in comparator, and is externally connected to a PID algorithm, the PID algorithm is an algorithm based on FPGS, the pin (1) of the chip (U1) is connected to the TMAIN signal output terminal, the pin (44) of the chip (U1) is connected to the AD-Vin power supply signal terminal, and the pin (42) of the chip (U1) is connected to the Curreng-V signal terminal.

6. The constant temperature heating control method based on the power and temperature double closed loop of the induction cooker as claimed in claim 1, characterized in that: The output end of the induction cooker is connected to an IGBT drive circuit, the source of the IGBT end of the IGBT drive circuit is connected to the pin (10) of the chip (U1), the gate of the IGBT end is connected to the power input, the drain of the IGBT end is connected to the input end of the diode (D8), and the output end of the diode (D8) is connected to the source of the IGBT end and then connected to the power output terminal to supply power to the working end of the induction cooker.

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