CN108449818A - A kind of heat-insulating lunch box based on DC low-voltage electromagnetic heating technique - Google Patents

Abstract

The invention discloses a thermal insulation bento box based on DC low-voltage electromagnetic heating technology, which includes an upper cover, an inner pot body, and a base, and a cavity is arranged inside the base, and the LC heating circuit of the control system includes capacitor C10, capacitor C11, inductor L1 and external heating Coil, inductor L1 is connected to capacitor C10, capacitor C11 and resistor R1 in the comparison circuit; one end of capacitor C10 is connected to inductor L1, capacitor C11 and resistor R1 in the comparison circuit; one end of capacitor C11 is connected to inductor L1, capacitor C10, connector P3 and comparison circuit The other end of the resistor R1 in the circuit is connected to the drain of the MOS transistor Q1 of the driving circuit, the connector P4 and the resistor R4 of the comparison circuit; the external heating coils are respectively connected to the connectors P3 and P4, and the external heating coils are set in the empty space of the base. In the cavity, the inner pot body is made of metal. The invention adopts DC power supply and IH heating control output, so that the heating body can heat up quickly and generate heat evenly.

Description

A thermal insulation bento box based on DC low-voltage electromagnetic heating technology

technical field

The invention relates to the technical field of household electrical appliances, in particular to a thermal insulation lunch box based on DC low-voltage electromagnetic heating technology.

Background technique

In the prior art, the thermal insulation bento box usually uses electric heating wire or electric heating film as the provider of the heat source to heat and keep the food in the bento. Such as the Chinese invention patent portable self-heating lunch box with the application number of 99123712.9 issued on May 23, 2001, a heating device is arranged under the lunch box, and the heating device is provided with a storage battery, which uses the storage battery to provide electric energy, and generates heat by electric heating. The way of steam directly or indirectly heats the food stored in the lunch box, and the steam is obtained by heating the clear water in the water container in the self-heating lunch box. Although it can provide heat to heat the food, because it has its own storage battery, the volume of the product is relatively large, and the circuit structure is also relatively complicated. Other existing electric heating type heat preservation lunch boxes are mostly set on the lower part of the lunch box with heating wire or membrane heater, and there are also temperature limiting parts using bimetallic strips or PTC as temperature limiting parts. The heater passes through the temperature limiting part. Electrically connected to mains. The disadvantage of this electric lunch box is that it lacks portability and needs to be used indoors where there are power outlets.

Contents of the invention

The purpose of the present invention is to provide a lightweight and portable heat preservation bento box based on DC low-voltage electromagnetic heating technology. The LC resonant circuit is used to convert low-voltage direct current into high-voltage and high-frequency alternating current exceeding audio frequency, and the high-voltage and high-frequency alternating current is added to the electromagnetic induction. On the heating coil, a high-frequency alternating magnetic field is generated, which generates a strong eddy current in the metal inner pot of the bento box. The conversion of electric energy to heat energy is completed when the eddy current overcomes the internal resistance of the pot and flows. To overcome the deficiencies in the prior art.

The technical solution of the present invention to solve the technical problem is: a thermal insulation lunch box based on DC low-voltage electromagnetic heating technology, the thermal insulation lunch box includes an upper cover, an inner pot body, a base, and a control system. In the cavity, a cavity is set inside the base. The control system includes a CUP program control circuit, a drive circuit, a temperature detection circuit, a low-voltage safety power supply circuit, an LC vibration high-power heating circuit, and a comparison circuit. The LC vibration high-power heating circuit includes a capacitor C10, capacitor C11, inductor L1 and an external heating coil, the comparison circuit includes resistors R1, R2, R4, R5, capacitors C9, C14; one end of the inductor L1 is connected to the positive pole of the power supply VDD1, and the other end is connected to the capacitor C10, capacitor C11 and the comparison circuit One end of the capacitor C10 is connected to the inductor L1, the capacitor C11 and the resistor R1 in the comparison circuit; one end of the capacitor C11 is connected to the inductor L1, the capacitor C10, the connector P3 and the resistor R1 in the comparison circuit. The other end is connected to the drain of the MOS transistor Q1 of the drive circuit, the connector P4 and the resistor R4 of the comparison circuit; one end of the external heating coil is connected to the connector P3, and the other end is connected to the connector P4; the external heating coil is set on the base In the cavity, the inner pot body is made of metal.

The LC vibration high-power heating circuit includes capacitor C10, capacitor C11, inductor L1 and an external heating coil. One end of inductor L1 is connected to the positive pole of power supply VDD1, and the other end is connected to capacitor C10, capacitor C11 and resistor R1 in the comparison circuit; one end of capacitor C10 is connected to the inductor L1, capacitor C11, and resistor R1 in the comparison circuit; one end of capacitor C11 is connected to inductor L1, capacitor C10, connector P3, and resistor R1 in the comparison circuit. The other end is connected to the drain of the MOS transistor Q1 of the driving circuit, the connector P4 and the resistor R4 of the comparison circuit; one end of the external heating coil is connected to the connector P3, and the other end is connected to the connector P4.

The driving circuit includes capacitor C15, capacitor C16, resistor R8, resistor R9, resistor R11, MOS transistor Q1, transistor Q2, transistor Q3, transistor Q4, the source of MOS transistor Q1 is connected to the capacitor C11 of the LC vibration high-power heating circuit and an external heating coil , The resistor R4 in the comparison circuit, the drain is connected to the ground, and the control stage is connected to the resistor R11; one end of the resistor R11 is connected to the control stage of the MOS transistor Q1, and the other end is connected to the emitter of the transistor Q2 and the transistor Q3; the collector of the transistor Q2 is connected to the power supply VDD2, and the transistor The emitter of Q2 is connected to the emitter of transistor Q3 and resistor R11, the base of transistor Q2 is connected to the base of transistor Q3, the collector of transistor Q4 is connected to resistor R8; the collector of transistor Q3 is grounded, and the emitter is connected to the emitter of transistor Q2 and resistor R11 , the base is connected to the base of the transistor Q2, the collector of the transistor Q4 and the resistor R8; the emitter of the transistor Q4 is grounded, the collector is connected to the base of the transistor Q2 and the transistor Q3 and the resistor R8, the base is connected to the resistor R9 and the CUP program control circuit One end of the capacitor C15 and capacitor C16 is connected to the power supply VDD2, and the other end is grounded; one end of the resistor R8 is connected to the power supply VDD2, the other end is connected to the base of the transistor Q2, the base of the transistor Q3 and the collector of the transistor Q4; one end of the resistor R9 is connected to the power supply VDD2, and the other end One end is connected to the base of the triode Q4 and the CUP program control circuit.

The buzzer circuit includes a buzzer LS1 and a capacitor C114. One end of the buzzer LS1 is connected to the power supply VDD3, the other end is connected to the positive electrode of the capacitor C114, and the other end of the capacitor C114 is connected to the CUP program control circuit.

The CUP program control circuit includes an integrated chip U1, a capacitor C7 and a capacitor C8. The first end of the integrated chip U1 is connected to the third end, the second end is grounded, and the third end is connected to the negative pole of the buzzer circuit capacitor C114; The five terminals are connected to the button input circuit, the sixth terminal is suspended; the seventh terminal is connected to the power supply VDD3, the eighth terminal is connected to the first pin of the connector P21; the ninth terminal is connected to the power supply VDD3; the tenth terminal is connected to the temperature detection circuit, the eleventh, The twelfth terminal is respectively connected to the N poles of the light-emitting diode L2 and the light-emitting diode L3 of the breathing light circuit, the thirteenth terminal is connected to the first terminal of the chip; the fourteenth terminal is connected to the resistor R1, the resistor R2 and the capacitor C9 of the comparison circuit; The fifteenth terminal is connected to the resistor R4 of the comparison circuit, the fifth resistor R5 and the capacitor C14; the sixteenth terminal is connected to the resistor R9 of the drive circuit and the base of the transistor Q4; one terminal of the capacitor C7 and capacitor C8 is connected to the power supply VDD3, and the other terminal is grounded.

The breathing light circuit includes light-emitting diodes L2, L3, resistors R13, R14, the P pole of the light-emitting diode L2 is connected to the resistor R13, and the N pole is connected to the CUP program control circuit; the P pole of the light-emitting diode L3 is connected to the resistor R14, and the N pole is connected to the CUP program control circuit One end of the resistor R13 is connected to the P pole of the light emitting diode L2, one end is connected to the power supply VDD3, one end of the resistor R14 is connected to the P pole of the light emitting diode L3, and the other end is connected to the power supply VDD3.

The temperature detection circuit includes resistors R3, R6, capacitors C12, C13, and connector P20. One end of resistor R3 is connected to resistor R6, capacitor C12, and connector P20. The other end of resistor R3 is connected to power supply VDD3; one end of resistor R6 is connected to resistor R3, capacitor C12, Connector P20, the other end is connected to capacitor C13 and CUP program control circuit; one end of connector P20 is connected to resistor R3, capacitor C12, resistor R6, and the other end is connected to ground; one end of capacitor C12 is connected to resistor R3, connector P20, resistor R6, and the other end Connect to ground; capacitor C13 is connected to resistor R6 and CUP program control circuit.

The low-voltage safety power supply circuit includes capacitors C1, C2, C3, C4, C5, C6 and voltage regulator tubes VR1, VR2. One end of C1 and C2 is connected to the input terminal of power supply VDD1 and voltage regulator tube VR1, and the other end is grounded. Capacitors C3 and C4 Connect the output terminal of the regulator tube VR1 and the input terminal of the regulator tube VR2 respectively; the capacitors C5 and C6 are connected to the power supply VDD3 and the output terminal of the regulator tube VR2; the input terminal of the regulator tube VR1 is connected to the power supply VDD1 and capacitors C1, C2, and VR1 The third end of the capacitor is connected to the input end of the capacitor C3, C4 and the regulator tube VR2.

The comparison circuit includes resistors R1, R2, R4, R5, capacitors C9, and C14. One end of resistor R1 is connected to capacitors C10, C11 and an external heating coil, and the other end is connected to capacitor C9, resistor R2, and the CUP program control circuit; one end of resistor R4 is connected to capacitor C11 , the drain of MOS tube Q1 and the external heating coil, the other end is connected to C14, R5 and CUP program control circuit; resistor R2 is connected to R1, C9 and CUP program control circuit; resistor R5 is connected to R4, C14 and CUP program control circuit, capacitor C9 Connect resistors R1, R2 and CUP program control circuit; capacitor C14 connects resistors R4, R5 and CUP program control circuit.

The button input circuit includes buttons S2 and S3, one end of the buttons S2 and S3 is connected to the CUP program control circuit, and the other end is connected to the ground.

The beneficial effects of the present invention are:

1) The present invention improves on the existing problems of the traditional insulated bento box, such as not being easy to carry or occupying a large space, and uses electromagnetic IH heating technology to heat and balance the performance so that the entire metal inner pot becomes a heat source, and cooperates with software to accurately control the temperature temperature. The error is controlled at about 2 degrees. In terms of energy saving, the dormancy technology of the chip is used to cooperate with the precise control of the software to achieve the purpose of energy saving.

2) The present invention uses LC resonant circuit to transform low-voltage direct current into high-voltage and high-frequency alternating current exceeding audio frequency, and adds the high-voltage and high-frequency alternating current to the electromagnetic induction heating coil, thereby generating high-frequency alternating magnetic field, whose magnetic field lines penetrate the metal The pot body generates a large eddy current in the pot body. The conversion of electric energy to heat energy is completed when the eddy current overcomes the internal resistance of the pot and flows.

3) The current electromagnetic IH heating technology has been widely used in home appliances such as induction cooker and rice cooker. One thing they have in common is that the power supply uses power frequency mains. This power supply method has great advantages in some portable and mobile occasions. limitations. However, the present invention adopts a low-voltage direct current power supply to make the technology suitable for portable and mobile occasions. The control circuit in the present invention is suitable for DC power supply below 38V, and ordinary batteries can also meet the requirements, achieving high-power IH heating control output, and making the heating body heat up quickly and evenly.

Description of drawings

Fig. 1 is the functional block diagram of the thermal insulation bento box circuit of the present invention.

Fig. 2 is a circuit diagram of the thermal insulation bento box of the present invention.

Fig. 3 is a power supply circuit diagram of a low-voltage safe power supply for the thermal insulation bento box of the present invention.

Fig. 4 is a temperature detection circuit diagram of the thermal insulation bento box of the present invention.

Fig. 5 is a circuit diagram of the breathing light of the thermal insulation bento box of the present invention.

Fig. 6 is a circuit diagram of the button input circuit and the CUP program control circuit of the thermal insulation bento box of the present invention.

Fig. 7 is a driving circuit diagram of the thermal insulation bento box of the present invention.

Fig. 8 is the LC vibration high-power heating circuit and comparison circuit diagram of the thermal insulation bento box of the present invention.

Fig. 9 is a circuit diagram of the buzzer of the thermal insulation bento box of the present invention.

Fig. 10 is a structural schematic diagram of the bento box of the present invention.

Fig. 11 is a schematic diagram of the installation of the external heating coil of the bento box of the present invention.

Fig. 12 is another schematic diagram of the installation of the external heating coil of the bento box of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection; it can also be a detachable connection. Connection, or integral connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

Referring to Figures 1-9, the control circuit of the thermal insulation bento box of the present invention includes: a CUP program control circuit, a drive circuit, a temperature detection circuit, a low-voltage safety power supply circuit, an LC vibration high-power heating circuit, a comparison circuit, and the like. Among them, the LC vibration high-power heating circuit includes capacitor C10, capacitor C11, inductor L1 and an external heating coil, and the comparison circuit includes resistors R1, R2, R4, R5, capacitors C9, C14; one end of the inductor L1 is connected to the positive pole of the power supply VDD1, and the other end Connect capacitor C10, capacitor C11, and resistor R1 in the comparison circuit; one end of capacitor C10 is connected to inductor L1, capacitor C11, and resistor R1 in the comparison circuit, and the other end is connected to ground; one end of capacitor C11 is connected to inductor L1, capacitor C10, and connector P3 and resistor R1 in the comparator circuit. The other end is connected to the drain of the MOS transistor Q1 of the driving circuit, the connector P4 and the resistor R4 of the comparison circuit; one end of the external heating coil is connected to the connector P3, and the other end is connected to the connector P4. This circuit is the key circuit of the whole system. The purpose is to generate a resonant current. This high-frequency resonant current generates an alternating magnetic flux in the coil, thereby generating eddy currents in the pot.

Low-voltage safety power supply circuit: the circuit is composed of capacitors C1, C2, C3, C4, C5, C6, and VR1, VR2. Among them, the Vout terminals of VR1 and VR2 can obtain the voltage required by the project according to actual needs. They provide the required stable voltage for the rest of the circuit blocks.

Temperature detection circuit: composed of resistors R3, R6, capacitors C12, C13, and P2. Among them, P20 and R3 are connected in series, and P20 is connected with an external temperature sensor. The CPU reads the divided voltage value and performs analog-to-digital conversion. R6, C12, and C13 form a filter circuit, which can also be changed into other similar filter circuits.

Breathing light circuit: composed of inductors L2, L3 and resistors R13, R14. Controlled by the CPU, it is used to indicate the current working status.

Drive circuit: a push-pull circuit composed of Q1, Q2, Q3, Q4, C15, C16, R8, R9, and R11. The purpose of setting is to convert the control signal PPG of CUP into an acceptable signal that can drive Q1 (MOS transistor, thyristor, IGBT transistor). Q1 is a key device of the system.

Detection comparison circuit: composed of R1.R2, R4, R5 and C9, C14. The purpose of this circuit is to detect the timing of the resonant voltage to the comparator, and the comparator will inform the CPU of the information obtained through comparison. After receiving the information from the comparator, the CPU will output the control signal to the drive circuit in time at the specified time.

CUP program control circuit: composed of U1, C7, and C8.

Buzzer circuit: composed of LS1 and C114. The purpose is to provide an acoustic signal to the outside world.

The purpose of the low-voltage safety power supply circuit is to provide various required power supplies to the drive circuit, the CUP control circuit and other module circuits. The purpose of the temperature detection circuit is to sense the temperature of the heating component and provide an analog signal to the CUP control circuit, which is converted into a digital signal of temperature through the dedicated AD converter inside the CUP to complete the analog-to-digital conversion. So as to provide information for the next step of the CUP processing. The purpose of setting the breathing light circuit is to indicate to the outside world which working state the circuit is currently in. The purpose of the driving circuit setting is to precisely provide pulses to control the on-off of MOS transistors, thyristors, and IGBT transistors. The purpose of the LC resonant high power heating circuit setup is to generate vibration harmonics and an alternating magnetic field. The purpose of the detection comparison circuit setting is to detect the timing state of the LC vibration circuit and provide accurate PPG control signals for CPU control. The purpose of the CPU program control circuit is to coordinate and control the whole system. The purpose of the button input circuit setting is to enable the outside world to control the start and stop of the whole system. The purpose of the buzzer circuit setting is to provide sound information to the outside world. The key of the present invention lies in the use of DC power supply and key components C10, C11, L1, Q1 and comparison circuit.

The signal flow direction of the insulated bento box: the LC oscillating high-power heating circuit generates a resonant current, and the timing of the resonant voltage is detected by the detection comparison circuit, and provided to the comparator or CUP. After analysis, judgment and processing, the CUP releases the control signal PPG accurately. PPG controls the on-off of MOS tubes, thyristors, and IGBT tubes by controlling the drive circuit. The CPU displays the information through the breathing light according to the current working state. The key input circuit notifies the CPU by reading the external input information. The temperature detection circuit detects the temperature of the pot body and provides the information to the CPU to make a decision.

Referring to Figures 10-11, the thermal insulation bento box includes a top cover 1, an inner pot body 2 that can be used to hold cooked food (such as rice, vegetables, buns, etc.), a base 3 that can accommodate the above-mentioned inner pot body, and the inner pot body 2 is placed In the inner cavity 31 of the base 3, the inner pot body is a metal container with an opening facing upwards, which serves as a meal box, and hooking elements (such as clasps) are set on its side to fasten the metal inner pot body on the cover The upper cover opening on it. A cavity is set inside the base, and the cavity includes a side ring cavity and a bottom cavity. The external heating coil 4 of the LC vibration high-power heating circuit is installed in the side ring cavity, and the external heating coil is wound on the wall of the side ring cavity. Circuit board 5 and lithium battery 6. A switch and an indicator light (not shown) are set on the outer wall of the base, and an NTC temperature-sensing hole is set on the upper wall of the bottom cavity. The NTC temperature-sensing head protrudes upwards from the hole to sense the temperature of the inner pot. into the temperature detection circuit.

Referring to FIG. 12 , as an improvement, the external heating coil 4 can be set as a flat circular coil disk and placed on the upper part of the bottom cavity.

Although the embodiments of the present invention have been shown and described, those skilled in the art should understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalent replacements, and improvements made without creative work shall be included in the protection scope of the present invention.

Claims (8)

1. A thermal insulation bento box based on DC low-voltage electromagnetic heating technology, the thermal insulation lunch box includes a loam cake, an inner pot body, a base, and a control system, the inner pot body is placed in the inner cavity of the base, and a cavity is arranged inside the base, It is characterized in that: the control system includes a CUP program control circuit, a drive circuit, a temperature detection circuit, and also includes a low-voltage safety power supply circuit, an LC vibration high-power heating circuit, and a comparison circuit. The LC vibration high-power heating circuit includes a capacitor C10, a capacitor C11, inductor L1 and external heating coil, the comparison circuit includes resistors R1, R2, R4, R5, capacitors C9, C14; one end of inductor L1 is connected to the positive pole of power supply VDD1, and the other end is connected to capacitor C10, capacitor C11 and resistor R1 in the comparison circuit One end of capacitor C10 is connected to inductor L1, capacitor C11 and resistor R1 in the comparison circuit; one end of capacitor C11 is connected to inductor L1, capacitor C10, connector P3 and resistor R1 in the comparison circuit, and the other end is connected to the MOS transistor Q1 of the drive circuit The drain, the connector P4 and the resistance R4 of the comparison circuit; one end of the external heating coil is connected to the connector P3, and the other end is connected to the connector P4; the external heating coil is arranged in the cavity of the base, and the inner pot body is Made of metal. 2. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 1, characterized in that: one end of resistor R1 of the comparison circuit is connected to capacitors C10, C11 and an external heating coil, and the other end is connected to capacitor C9, resistor R2 and CUP program control circuit; one end of resistor R4 is connected to capacitor C11, the drain of MOS tube Q1 and an external heating coil, and the other end is connected to C14, R5 and CUP program control circuit; resistor R2 is connected to R1, C9 and CUP program control circuit; resistor R5 is connected to R4, C14 and the CUP program control circuit, the capacitor C9 is connected to the resistors R1, R2 and the CUP program control circuit; the capacitor C14 is connected to the resistors R4, R5 and the CUP program control circuit. 3. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that: the low-voltage safety power supply circuit includes capacitors C1, C2, C3, C4, C5, C6 and voltage regulator tubes VR1, VR2 One end of the capacitors C1 and C2 is connected to the power supply VDD1 and the input end of the regulator tube VR1, and the other end is grounded. The capacitors C3 and C4 are respectively connected to the output terminal of the regulator tube VR1 and the input terminal of the regulator tube VR2; VDD3 and the output terminal of the regulator tube VR2; the input terminal of the regulator tube VR1 is connected to the power supply VDD1 and capacitors C1 and C2, and the third terminal of VR1 is connected to the capacitors C3 and C4 and the input terminal of the regulator tube VR2. 4. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that: the drive circuit includes a capacitor C15, a capacitor C16, a resistor R8, a resistor R9, a resistor R11, a MOS transistor Q1, a triode Q2, Transistor Q3, triode Q4, the source of MOS tube Q1 is connected to the capacitor C11 of the LC vibration high-power heating circuit and the external heating coil, the resistor R4 in the comparison circuit, the drain is connected to the ground, the control stage is connected to the resistor R11; one end of the resistor R11 is connected to the MOS tube Q1 control stage, the other end is connected to the emitter of transistor Q2 and transistor Q3; the collector of transistor Q2 is connected to the power supply VDD2, the emitter of transistor Q2 is connected to the emitter of transistor Q3 and resistor R11, the base of transistor Q2 is connected to the base of transistor Q3, and the transistor The collector of Q4 and resistor R8; the collector of transistor Q3 is grounded, the emitter is connected to the emitter of transistor Q2 and resistor R11, the base is connected to the base of transistor Q2, the collector of transistor Q4 and resistor R8; the emitter of transistor Q4 is grounded, The collector is connected to the base of transistor Q2 and transistor Q3, resistor R8, and the base is connected to resistor R9 and the CUP program control circuit; one end of capacitor C15 and capacitor C16 is connected to power supply VDD2, and the other end is grounded; one end of resistor R8 is connected to power supply VDD2, and the other end is connected to The base of the transistor Q2, the base of the transistor Q3 and the collector of the transistor Q4; one end of the resistor R9 is connected to the power supply VDD2, and the other end is connected to the base of the transistor Q4 and the CUP program control circuit. 5. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that: the temperature detection circuit includes resistors R3, R6, capacitors C12, C13 and connector P20, one end of resistor R3 is connected to resistors R6, Capacitor C12, connector P20, the other end of resistor R3 is connected to power supply VDD3; one end of resistor R6 is connected to resistor R3, capacitor C12, and connector P20, and the other end is connected to capacitor C13 and CUP program control circuit; one end of connector P20 is connected to resistor R3 and capacitor C12 1. Resistor R6, the other end is connected to the ground; one end of the capacitor C12 is connected to the resistor R3, the connector P20, and the resistor R6, and the other end is connected to the ground; the capacitor C13 is connected to the resistor R6 and the CUP program control circuit. 6. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that it also includes a buzzer circuit, and the buzzer circuit includes a buzzer LS1 and a capacitor C114. One end of the buzzer LS1 is connected to the power supply VDD3, the other end is connected to the positive electrode of the capacitor C114, and the other end of the capacitor C114 is connected to the CUP program control circuit. 7. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that: it also includes a breathing light circuit, and the breathing light circuit includes light-emitting diodes L2, L3, resistors R13, R14, light-emitting diode L2 The P pole is connected to the resistor R13, and the N pole is connected to the CUP program control circuit; the P pole of the light-emitting diode L3 is connected to the resistor R14, and the N pole is connected to the CUP program control circuit. One end is connected to the P pole of the light emitting diode L3, and the other end is connected to the power supply VDD3. 8. The thermal insulation bento box based on DC low-voltage electromagnetic heating technology according to claim 2, characterized in that: it also includes a button input circuit, the button input circuit includes buttons S2 and S3, and one end of the buttons S2 and S3 is connected to the CUP program control circuit, with the other end connected to ground.