Low power automatic switching power main board

Abstract

The utility model relates to the technical field of electromagnetic stove discloses can realize low -power automatic switching power mainboard, include: the switching power supply that will alternating current convert for direct current and power supply for mainboard, realize the surge protection circuit that power output is closed when grid voltage exists transient high pressure, receive the PWM control signal of MCU, and drive IGBT module high -frequency switch operation's IGBT drive circuit, the MCU control circuit that is responsible for data acquisition, the pot bottom sensor detection circuit that is responsible for gathering pot bottom temperature data, the burning -in mouth that provides MCU program burning -in interface, the communication interface for connecting power mainboard and control board, realize the resonance capacitance switching circuit of dynamic switching resonance capacitance value, the utility model satisfies user can use high -power cooking, also can realize low -power automatic switching continuous heating's function, bid farewell to the problem of previous low -power intermittent heating.

Description

Technical Field

[0001] This utility model relates to the field of induction cooker technology, and more particularly to the field of power mainboards for induction cookers, specifically a power mainboard that can automatically switch power at low power. Background Technology

[0002] The power mainboard of an induction cooker is one of its core components, primarily responsible for the high-frequency conversion of electrical energy and controlling the heating process. The power mainboard of an induction cooker mainly includes an IGBT module, drive circuit, control chip, resonant capacitor, protection circuit, and power supply module.

[0003] A search revealed that patent application number CN202223134142.6 discloses a mainboard for a dual-head induction cooker, comprising a left MCU and a right MCU. The left MCU is connected to a left programming port, a left IGBT drive circuit, a left IGBT sensor detection circuit, and a left pot bottom sensor detection circuit. A switching power supply, a surge protection circuit, and a communication interface are connected in parallel between the left and right MCUs. The right MCU is connected to a right programming port, a right IGBT drive circuit, a right IGBT sensor detection circuit, and a right pot bottom sensor detection circuit. This invention, through the cooperation of the switching power supply, the left and right MCUs, the communication interface, and the left and right IGBT drive circuits, can control the heating functions of the left and right boilers. Assembly only requires assembling one mainboard, simplifying the assembly structure. Through the cooperation of the left and right MCUs and the surge protection circuit, when there is a momentary high voltage in the mains voltage, the left and right MCUs will issue a command to shut down the power output, protecting the circuit and improving safety.

[0004] Traditional induction cookers use intermittent heating in their low-power mode, which results in low heating efficiency and uneven heating. Therefore, we need to propose a mainboard that can automatically switch power at low power. Utility Model Content

[0005] The purpose of this utility model is to provide a mainboard that can automatically switch power at low power, so as to meet the needs of users to use high power cooking and also achieve the function of continuous heating with automatic switching at low power, thus eliminating the problem of intermittent heating at low power in the past and solving the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a mainboard capable of automatic power switching under low power conditions, comprising:

[0007] A switching power supply that converts alternating current to direct current and powers the motherboard;

[0008] A surge protection circuit that shuts down power output when there is a momentary high voltage in the power grid;

[0009] An IGBT drive circuit that receives PWM control signals from the MCU and drives the IGBT module to operate at high frequency.

[0010] The MCU control circuit responsible for data acquisition;

[0011] The bottom-of-the-pot sensor detection circuit is responsible for collecting bottom-of-the-pot temperature data.

[0012] Provides a programming port for programming MCU programs;

[0013] Communication interface used to connect the power mainboard and the control board;

[0014] A resonant capacitor switching circuit that enables dynamic switching of resonant capacitor values;

[0015] The switching power supply, MCU control circuit, and IGBT drive circuit are connected in sequence. The programming port, MCU control circuit, and communication interface are connected in sequence. The bottom sensor detection circuit is electrically connected to the MCU control circuit. The surge protection circuit, MCU control circuit, and resonant capacitor switching circuit are connected in sequence.

[0016] Preferably, the MCU control circuit includes a chip U3, pin 5 of the chip U3 is connected to a resistor R26, pin 6 of the chip U3 is connected to a resistor R27, pin 13 of the chip U3 is connected to a resistor R127 and a diode D9, and pin 18 of the chip U3 is connected to a capacitor EC105, a capacitor C121 and a resistor R125 arranged in parallel.

[0017] Preferably, the switching power supply includes a chip U2, a transformer T1, a voltage regulator U5, and a voltage regulator U6. Pin 5 of the chip U2 is connected to pin 1 of the transformer T1. Diodes D16 and D17 are connected between pin 4 of the chip U2 and pin 5 of the transformer T1. Diodes D15 and ZD2 are connected between pin 3 of the chip U2 and pin 5 of the transformer T1.

[0018] A diode D4 is connected to pin 6 of the transformer T1, a resistor R4 is connected to pin 1 of the voltage regulator U5, and a resistor R30 is connected to pin 1 of the voltage regulator U6. The resistors R4 and R30 and the diode D4 are connected together.

[0019] Preferably, the surge protection circuit includes a rectifier bridge DB1. A capacitor C11 is connected between pins 1 and 2 of the rectifier bridge DB1. A diode D1 and a diode D2 are also connected between pins 1 and 2 of the rectifier bridge DB1. The terminals of diodes D1 and D2 are respectively connected to a resistor R9, a capacitor C13 connected in parallel, and a resistor R10. One end of the resistor R9 is connected to a resistor R13, a capacitor EC1, a capacitor C888, and a capacitor C12 connected in parallel. The terminals of C13 and resistor R10 are connected to a resistor R15. One end of the resistor R15 is connected to a capacitor C15, a diode ZD4, and a resistor R17 and a resistor R20 connected in series.

[0020] Preferably, the IGBT driving circuit includes transistors Q7, Q16, and Q103. The emitter of transistor Q7 is connected to the emitter of transistor Q16, the base of transistor Q7 is connected to the base of transistor Q16, the emitter of transistor Q103 is connected to the collector of transistor Q16, and the collector of transistor Q103 is connected to the bases of transistors Q7 and Q16.

[0021] A resistor R105 and a resistor R126 are connected between the base and collector of the transistor Q7. One end of the resistor R105 is connected to a capacitor EC102 and a capacitor C122 connected in parallel. A resistor R112 is connected to the base of the transistor Q103. A resistor R111 is connected between the resistor R112 and the resistor R105.

[0022] Preferably, the pot bottom sensor detection circuit includes a connector CN19, with resistors R156 and R22 connected in series at pin 3 of the connector CN19. A resistor R45 and a capacitor C27 are connected in parallel at the connection terminals of resistors R156 and R22. The pot bottom sensor detection circuit also includes a thermistor RT2, with resistor R8 and capacitor C9 connected to its two ends respectively.

[0023] Preferably, the programming port includes a connector CN103, pin 2 of the connector CN103 is connected to a 5V power supply, pin 3 of the connector CN103 is connected to pin 3 of the chip U3, and pin 4 of the connector CN103 is connected to pin 4 of the chip U3.

[0024] Preferably, the communication interface includes a connector CN5 and a transistor Q6. The base of the transistor Q6 is connected to a resistor R16, and a capacitor C10 is connected between the collector and emitter of the transistor Q6. Pin 2 of the connector CN5 is connected to the collector of the transistor Q6.

[0025] Preferably, the resonant capacitor switching circuit includes a relay K2, a transistor Q13 connected to the relay K2, and an induction cooker power transistor IGBT2. A resistor R108 and a diode Z2 are connected in parallel between the base and emitter of the induction cooker power transistor IGBT2. A capacitor C6, a resistor R1000, and capacitors C2A and C2B connected in parallel are connected between the collector and emitter of the induction cooker power transistor IGBT.

[0026] The capacitor C2B is connected to resistors R2 and R6 at its two ends, and both resistors R2 and R6 are connected to pin 16 of chip U3.

[0027] Compared with the prior art, the beneficial effects of this utility model are:

[0028] 1. This utility model satisfies the user's need to use high-power cooking while also achieving automatic switching to continuous heating at low power, thus eliminating the previous problem of intermittent heating at low power. Attached Figure Description

[0029] Figure 1 This is a system block diagram of the present invention;

[0030] Figure 2 This is the circuit diagram of the switching power supply of this utility model;

[0031] Figure 3 This is a circuit diagram of the surge protection circuit of this utility model;

[0032] Figure 4 This is a circuit diagram of the IGBT drive circuit of this utility model;

[0033] Figure 5 This is a circuit diagram of the MCU control circuit of this utility model;

[0034] Figure 6 This is a circuit diagram of the detection circuit for the bottom sensor of this utility model;

[0035] Figure 7 This is the circuit diagram of the programming port of this utility model;

[0036] Figure 8 This is a circuit diagram of the communication interface of this utility model;

[0037] Figure 9 This is a circuit diagram of the resonant capacitor switching circuit of this utility model. Detailed Implementation

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

[0039] Please see Figure 1-9 This utility model provides a technical solution: a mainboard capable of automatically switching power at low power levels, comprising:

[0040] A switching power supply that converts alternating current to direct current and powers the motherboard;

[0041] The switching power supply includes chip U2, transformer T1, voltage regulator U5, and voltage regulator U6. Pin 5 of chip U2 is connected to pin 1 of transformer T1. Diodes D16 and D17 are connected between pin 4 of chip U2 and pin 5 of transformer T1. Diodes D15 and ZD2 are connected between pin 3 of chip U2 and pin 5 of transformer T1.

[0042] A diode D4 is connected to pin 6 of the transformer T1, a resistor R4 is connected to pin 1 of the voltage regulator U5, and a resistor R30 is connected to pin 1 of the voltage regulator U6. The resistors R4 and R30 and the diode D4 are connected together.

[0043] like Figure 1 As shown, rectifier diode D3 rectifies the input AC voltage into pulsating DC voltage, connectors (CN1, CN2) are used for circuit connection, resistor R3 is the input current limiting resistor to protect subsequent circuit components, and capacitor C8 is the input filter capacitor to smooth the DC voltage and reduce ripple.

[0044] Chip U2 is a switching power supply controller IC that controls the power supply's operating state and timing. Transformer T1 provides electrical isolation and energy transfer. Diode D14 converts the AC output from transformer T1 into DC. Diode D16 improves rectification efficiency, and diode D17 is used for protection or control. Zener diode ZD2 provides voltage reference or overvoltage protection.

[0045] Capacitors (EC2, EC3, EC5) are used for filtering and stabilizing the output voltage. Capacitors (C3A, C3, C4, EC4) further reduce the output ripple. Regulator U5 converts the higher DC voltage into a stable 5V output. Resistor R23 is used to set the output voltage or as a bias resistor.

[0046] A surge protection circuit that shuts down power output when there is a momentary high voltage in the power grid;

[0047] The surge protection circuit includes a rectifier bridge DB1. A capacitor C11 is connected between pins 1 and 2 of the rectifier bridge DB1. A diode D1 and a diode D2 are also connected between pins 1 and 2 of the rectifier bridge DB1. The terminals of diodes D1 and D2 are respectively connected to a resistor R9, a capacitor C13 connected in parallel, and a resistor R10. One end of the resistor R9 is connected to a resistor R13, a capacitor EC1, a capacitor C888, and a capacitor C12 connected in parallel. The terminals of C13 and resistor R10 are connected to a resistor R15. One end of the resistor R15 is connected to a capacitor C15, a diode ZD4, and a resistor R17 and a resistor R20 connected in series.

[0048] L and N are the input terminals for AC power, namely the live wire and the neutral wire, respectively. Capacitor C11 is used to filter out high-frequency interference signals on the power line. Rectifier bridge DB1 converts AC power to DC power. Diodes D1 and D2 are used as rectifier elements to convert AC power to pulsating DC power.

[0049] Resistor R9 is used for current limiting or voltage division, resistor R10 is used for RC filter network or discharge circuit, capacitor C13 is used for filtering and energy storage, resistor R15 is used for current limiting or voltage division, and resistor R17 is used for precise current limiting or voltage division.

[0050] Capacitor EC1 is used to smooth DC voltage, diode ZD4 provides a stable reference voltage and overvoltage protection, and capacitor C16 is used for filtering or preventing high-frequency interference. The jumper is a jumper connector used to set the circuit's operating mode or configuration parameters.

[0051] An IGBT drive circuit that receives PWM control signals from the MCU and drives the IGBT module to operate at high frequency.

[0052] The IGBT driving circuit includes transistors Q7, Q16, and Q103. The emitter of transistor Q7 is connected to the emitter of transistor Q16, the base of transistor Q7 is connected to the base of transistor Q16, the emitter of transistor Q103 is connected to the collector of transistor Q16, and the collector of transistor Q103 is connected to the bases of transistors Q7 and Q16.

[0053] A resistor R105 and a resistor R126 are connected between the base and collector of the transistor Q7. One end of the resistor R105 is connected to a capacitor EC102 and a capacitor C122 connected in parallel. A resistor R112 is connected to the base of the transistor Q103. A resistor R111 is connected between the resistor R112 and the resistor R105.

[0054] Transistor Q7 is used for level shifting and signal inversion, forming part of the Darlington transistor structure. Transistor Q16 works in conjunction with transistor Q7 to form a driver stage, providing sufficient current drive capability. Transistor Q103 is used for signal transmission and power amplification. Diode D15 is used as a freewheeling diode to protect the IGBT from reverse voltage spikes.

[0055] Resistor R105 limits the base current of transistor Q7, resistor R111 is used to set the bias voltage, resistor R112 is used to precisely control the output current, resistor R126 is used for current detection or limiting, and capacitor C122 is used to eliminate high-frequency noise and stabilize the signal.

[0056] The MCU control circuit responsible for data acquisition;

[0057] The MCU control circuit includes a chip U3. Pin 5 of the chip U3 is connected to a resistor R26, pin 6 of the chip U3 is connected to a resistor R27, pin 13 of the chip U3 is connected to a resistor R127 and a diode D9, and pin 18 of the chip U3 is connected to a capacitor EC105, a capacitor C121, and a resistor R125 arranged in parallel.

[0058] like Figure 5 As shown, resistors (R26, R27, R28) are used as pull-up or pull-down resistors to determine the default level of the pins, enhance signal stability, and prevent signal lines from floating. Resistor R127 is used for voltage division and current limiting. Capacitor C12 is used for filtering, removing high-frequency noise from the power supply or signal lines, making the circuit more stable. Diode D9 is a fast-switching diode, commonly used to protect circuits from reverse voltage surges. For example, in inductive load circuits such as relays, it is used for freewheeling to protect other components from damage by induced electromotive force. The jumper interface in the MCU control circuit allows for different connection states by inserting jumper caps or shorting pins. This can be used to configure circuit parameters, select different operating modes, or perform circuit debugging. Capacitor EC105 is an electrolytic capacitor mainly used for power supply filtering, storing and releasing electrical energy, stabilizing the power supply voltage, and reducing the impact of power supply ripple on the circuit.

[0059] The bottom-of-the-pot sensor detection circuit is responsible for collecting bottom-of-the-pot temperature data.

[0060] The pot bottom sensor detection circuit includes a connector CN19, with resistors R156 and R22 connected in series at pin 3 of the connector CN19. Resistors R45 and C27 are connected in parallel at the connection terminals of resistors R156 and R22. The pot bottom sensor detection circuit also includes a thermistor RT2, with resistors R8 and C9 connected at its two ends.

[0061] like Figure 6 As shown, CS is the chip select signal, used to select a specific chip or module for communication; DAT is the data signal line, used to transmit data; CLK is the clock signal line, used to synchronize data transmission; and resistors (R8, R13, R16) are pull-up resistors, used to keep the signal lines at a high level until an external device pulls them low.

[0062] Thermistor RT2 is used to detect changes in the temperature of the pot bottom. Its resistance changes with temperature. Resistors R15 and R16 are used to maintain a high level on the signal line. Pin GUOUT is the output signal used to transmit the detection result.

[0063] Provides a programming port for programming MCU programs;

[0064] The programming port includes connector CN103, pin 2 of connector CN103 is connected to a 5V power supply, pin 3 of connector CN103 is connected to pin 3 of chip U3, and pin 4 of connector CN103 is connected to pin 4 of chip U3.

[0065] like Figure 7 As shown, DSDA and DSCL are I 2 The C-channel communication bus is used as the serial data line (DSDA) and serial clock line (DSCL) for communication between chips. GU01 T and IGBT T1 are signals associated with the IGBT (Insulated Gate Bipolar Transistor). IGBT T1 is the main power switching element, while GU01 T is its drive control signal.

[0066] Communication interface used to connect the power mainboard and the control board;

[0067] The communication interface includes a connector CN5 and a transistor Q6. The base of the transistor Q6 is connected to a resistor R16, and a capacitor C10 is connected between the collector and emitter of the transistor Q6. Pin 2 of the connector CN5 is connected to the collector of the transistor Q6.

[0068] like Figure 8 As shown, transistor Q6 acts as a switch in the circuit. When there is a suitable electrical signal at its base, transistor Q6 conducts, pulling the RXD signal low; when there is no signal at the base of transistor Q6, transistor Q6 is cut off, and the RXD signal is kept high through the pull-up resistor.

[0069] Resistor R14 serves to limit current and protect the transistor, preventing excessive current from damaging it. Resistor R16 is a pull-up resistor, keeping the RXD signal at a high level when there is no transmission signal.

[0070] Inductors (L1, L2, L3) are used to suppress high-frequency interference and act as filters to ensure the purity of communication signals.

[0071] When there is a high-level signal at the TX terminal, transistor Q6 is turned on, pulling the RXD signal low, thus sending a low-level signal to the external device; when the TX terminal is low, transistor Q6 is turned off, and RXD is pulled up to a high level through R16, thus sending a high-level signal to the external device.

[0072] Signals sent by external devices enter the circuit through the CN5 connector. After passing through a filter circuit composed of inductors L1 and L2 and capacitor C10, further signal processing may be performed.

[0073] The TEST jumper allows you to short-circuit certain test points when needed, facilitating circuit debugging and testing.

[0074] A resonant capacitor switching circuit that enables dynamic switching of resonant capacitor values;

[0075] The resonant capacitor switching circuit includes a relay K2, a transistor Q13 connected to the relay K2, and an induction cooker power transistor IGBT2. A resistor R108 and a diode Z2 are connected in parallel between the base and emitter of the induction cooker power transistor IGBT2. A capacitor C6, a resistor R1000, and capacitors C2A and C2B connected in parallel are connected between the collector and emitter of the induction cooker power transistor IGBT.

[0076] The two ends of capacitor C2B are connected to resistors R2 and R6, respectively, and both resistors R2 and R6 are connected to pin 16 of chip U3. Inductor L5 is also connected to the terminals of capacitors C2B and C6.

[0077] like Figure 9 As shown, when the induction cooker is at high power, relay K2 is activated, and resonant capacitors C2A and C2B work simultaneously. When the user uses low power, relay K2 automatically disconnects, and only capacitor C2B works. It forms an LC oscillating capacitor with the induction coil, which can achieve continuous heating at low power.

[0078] Inductor L5 is a resonant inductor, which, together with resonant capacitors (C2A, C2B), forms a resonant circuit. Transistor Q13 is used to drive relays or other loads, and the induction cooker power transistor IGBT2 is a power switching device used for high-frequency switching operation to control the on / off state of the resonant circuit.

[0079] The switching power supply, MCU control circuit, and IGBT drive circuit are connected in sequence. The programming port, MCU control circuit, and communication interface are connected in sequence. The bottom sensor detection circuit is electrically connected to the MCU control circuit. The surge protection circuit, MCU control circuit, and resonant capacitor switching circuit are connected in sequence.

[0080] When using:

[0081] The switching power supply converts the input 220V AC power to 5V (for the MCU, sensors, etc.) and 15V (for the IGBT driver) to power the entire system. The MCU starts a self-test program, initializes various peripherals (such as ADC and PWM modules), and waits for user input commands.

[0082] The bottom sensor detection circuit monitors the bottom temperature of the pot in real time. If a valid pot (iron and within a reasonable temperature range) is detected, a signal is sent to the MCU to allow entry into heating mode. If no pot is available or the pot is non-compliant, the MCU notifies the control board of an error (e.g., E1) via the communication interface.

[0083] The MCU dynamically adjusts the PWM signal based on the temperature data fed back by the sensor at the bottom of the pot to maintain the stability of the set power. If a voltage fluctuation (such as a surge) is detected in the mains voltage, the MCU quickly cuts off the IGBT drive signal through the surge protection circuit to protect the hardware.

[0084] The surge protection circuit monitors the grid voltage in real time. If a momentary high voltage (such as a lightning strike) is detected, it immediately sends an interrupt signal to the MCU. The MCU triggers the protection logic: shuts down the IGBT drive output → reports a fault code through the communication interface → waits for the grid to recover and then restarts.

[0085] The bottom sensor continuously monitors the temperature of the cookware. If the temperature exceeds the limit (e.g., dry burning), the MCU immediately reduces the frequency or stops heating. The MCU has built-in over-temperature protection: if the temperature of the MCU or the IGBT temperature sensor (requires additional circuitry) exceeds the limit, the power output is forcibly shut off.

[0086] The IGBT driver circuit has a built-in current sampling resistor to detect the IGBT current in real time. If the current is abnormal (such as a short circuit), the driver circuit triggers a soft shutdown and sends an alarm signal to the MCU to trigger the shutdown protection.

[0087] The bottom sensor works in conjunction with the MCU to input temperature data for power regulation and protection decisions; the MCU and IGBT drive circuit work together to control the IGBT switching with PWM signals; and the MCU and communication interface work together to send real-time data (temperature, power, etc.) or fault codes to the control board.

[0088] After the user issues a command, the communication interface receives the command and passes it to the MCU to set parameters such as power and mode. During operation, the MCU transmits signals to the resonant capacitor switching circuit to dynamically adjust the capacitor value to adapt to the power requirements.

[0089] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A motherboard capable of automatic power switching at low power levels, characterized in that: include: A switching power supply that converts alternating current to direct current and powers the motherboard; A surge protection circuit that shuts down power output when there is a momentary high voltage in the power grid; An IGBT drive circuit that receives PWM control signals from the MCU and drives the IGBT module to operate at high frequency. The MCU control circuit responsible for data acquisition; The bottom-of-the-pot sensor detection circuit is responsible for collecting bottom-of-the-pot temperature data. Provides a programming port for programming MCU programs; Communication interface used to connect the power mainboard and the control board; A resonant capacitor switching circuit that enables dynamic switching of resonant capacitor values; The switching power supply, MCU control circuit, and IGBT drive circuit are connected in sequence. The programming port, MCU control circuit, and communication interface are connected in sequence. The bottom sensor detection circuit is electrically connected to the MCU control circuit. The surge protection circuit, MCU control circuit, and resonant capacitor switching circuit are connected in sequence.

2. The motherboard capable of automatic low-power switching according to claim 1, characterized in that: The MCU control circuit includes a chip U3. Pin 5 of the chip U3 is connected to a resistor R26, pin 6 of the chip U3 is connected to a resistor R27, pin 13 of the chip U3 is connected to a resistor R127 and a diode D9, and pin 18 of the chip U3 is connected to a capacitor EC105, a capacitor C121, and a resistor R125 arranged in parallel.

3. The motherboard capable of automatic low-power switching according to claim 2, characterized in that: The switching power supply includes chip U2, transformer T1, voltage regulator U5, and voltage regulator U6. Pin 5 of chip U2 is connected to pin 1 of transformer T1. Diodes D16 and D17 are connected between pin 4 of chip U2 and pin 5 of transformer T1. Diodes D15 and ZD2 are connected between pin 3 of chip U2 and pin 5 of transformer T1. A diode D4 is connected to pin 6 of the transformer T1, a resistor R4 is connected to pin 1 of the voltage regulator U5, and a resistor R30 is connected to pin 1 of the voltage regulator U6. The resistors R4 and R30 and the diode D4 are connected together.

4. The motherboard capable of automatic low-power switching according to claim 3, characterized in that: The surge protection circuit includes a rectifier bridge DB1. A capacitor C11 is connected between pins 1 and 2 of the rectifier bridge DB1. A diode D1 and a diode D2 are also connected between pins 1 and 2 of the rectifier bridge DB1. The terminals of diodes D1 and D2 are respectively connected to a resistor R9, a capacitor C13 connected in parallel, and a resistor R10. One end of the resistor R9 is connected to a resistor R13, a capacitor EC1, a capacitor C888, and a capacitor C12 connected in parallel. The terminals of C13 and resistor R10 are connected to a resistor R15. One end of the resistor R15 is connected to a capacitor C15, a diode ZD4, and a resistor R17 and a resistor R20 connected in series.

5. The motherboard capable of automatic low-power switching according to claim 4, characterized in that: The IGBT driving circuit includes transistors Q7, Q16, and Q103. The emitter of transistor Q7 is connected to the emitter of transistor Q16, the base of transistor Q7 is connected to the base of transistor Q16, the emitter of transistor Q103 is connected to the collector of transistor Q16, and the collector of transistor Q103 is connected to the bases of transistors Q7 and Q16. A resistor R105 and a resistor R126 are connected between the base and collector of the transistor Q7. One end of the resistor R105 is connected to a capacitor EC102 and a capacitor C122 connected in parallel. A resistor R112 is connected to the base of the transistor Q103. A resistor R111 is connected between the resistor R112 and the resistor R105.

6. The motherboard capable of automatic low-power switching according to claim 5, characterized in that: The pot bottom sensor detection circuit includes a connector CN19, with resistors R156 and R22 connected in series at pin 3 of the connector CN19. Resistors R45 and C27 are connected in parallel at the connection terminals of resistors R156 and R22. The pot bottom sensor detection circuit also includes a thermistor RT2, with resistors R8 and C9 connected at its two ends.

7. The motherboard capable of automatic low-power switching according to claim 6, characterized in that: The programming port includes connector CN103, pin 2 of connector CN103 is connected to a 5V power supply, pin 3 of connector CN103 is connected to pin 3 of chip U3, and pin 4 of connector CN103 is connected to pin 4 of chip U3.

8. The motherboard capable of automatic low-power switching according to claim 7, characterized in that: The communication interface includes a connector CN5 and a transistor Q6. The base of the transistor Q6 is connected to a resistor R16, and a capacitor C10 is connected between the collector and emitter of the transistor Q6. Pin 2 of the connector CN5 is connected to the collector of the transistor Q6.

9. The motherboard capable of automatic low-power switching according to claim 8, characterized in that: The resonant capacitor switching circuit includes a relay K2, a transistor Q13 connected to the relay K2, and an induction cooker power transistor IGBT2. A resistor R108 and a diode Z2 are connected in parallel between the base and emitter of the induction cooker power transistor IGBT2. A capacitor C6, a resistor R1000, and capacitors C2A and C2B connected in parallel are connected between the collector and emitter of the induction cooker power transistor IGBT. The capacitor C2B is connected to resistors R2 and R6 at its two ends, and both resistors R2 and R6 are connected to pin 16 of chip U3.

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