A gas water heater control circuit

Abstract

The present invention discloses a gas water heater control circuit, comprising a power supply module, a flow detection module, a self-priming valve control module, a pulse discharge module, a flame detection module, a proportional valve control module, and a microcontroller. The proportional valve control module includes a proportional valve port, an operational amplifier U1, a switching transistor Q1, a resistor R1, and a voltage regulator. In this proportional valve control module, resistor R1 is used to collect the proportional valve coil current; the voltage regulator is used to control the output voltage amplitude based on the duty cycle of a PWM signal output by the microcontroller; and the operational amplifier U1 controls the on / off switching of the switching transistor Q1 based on the voltage signal transmitted by the voltage regulator and resistor R1, thereby achieving closed-loop control of the proportional valve and improving the stability of water flow in the gas water heater pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of gas water heaters, and more particularly to a gas water heater control circuit. Background Art

[0002] Gas water heaters are common hot water supply appliances. Existing gas water heaters are equipped with a water-gas linkage valve and a gas proportional valve. The water-gas linkage valve ensures that the gas control valve opens only when water pressure is sufficient and flowing through the heat exchanger. If water flow stops or pressure is insufficient, the gas supply is automatically cut off to prevent damage to the equipment due to water shortage. The gas proportional valve regulates the gas flow in the pipeline and controls the flow. The combination of the water-gas linkage valve and the gas proportional valve ensures constant temperature water supply when water flow is sufficient.

[0003] The proportional valve control circuit in the existing gas water heater does not adopt the closed-loop control form, which leads to unstable water flow in the water pipeline of the gas water heater, and further makes it difficult to stabilize the water temperature of the gas water heater. Summary of the Invention

[0004] In order to solve one or more of the above technical problems, an object of the present invention is to provide a gas water heater control circuit.

[0005] The technical solution adopted by the present invention to solve the problem is:

[0006] A gas water heater control circuit includes a power supply module, a flow detection module, a self-priming valve control module, a pulse discharge module, a flame detection module, a proportional valve control module and a microcontroller;

[0007] The power supply module is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module, the proportional valve control module and the microcontroller, and the microcontroller is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module and the proportional valve control module;

[0008] The proportional valve control module includes a proportional valve port, an operational amplifier U1, a switch tube Q1, a resistor R1 and a voltage regulating unit. The proportional valve ports are configured with two, the microcontroller is connected to the voltage regulating unit, and the voltage regulating unit is configured to control the voltage amplitude of its output according to the duty cycle of the PWM signal output by the microcontroller. The voltage regulating unit is connected to the non-inverting input terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the gate of the switch tube Q1, the source of the switch tube Q1 is connected to the power module, the drain of the switch tube Q1 is connected to one of the proportional valve ports, and the other proportional valve port is connected to the inverting input terminal of the operational amplifier U1, and is connected to the ground terminal through the resistor R1.

[0009] As a further improvement of the above technical solution, the voltage regulating unit includes an NPN transistor Q2, a resistor R2, a resistor R3, a resistor R4 and a capacitor C1, the microcontroller is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the ground, the resistor R2 and the resistor R3 are connected in series between the power module and the ground, the collector of the transistor Q2 is connected to the connection point of the resistor R2 and the resistor R3, one end of the resistor R4 is connected to the collector of the transistor Q2, the other end of the resistor R4 is connected to the ground through the capacitor C1, and the non-inverting input of the operational amplifier U1 is connected to the connection point of the resistor R4 and the capacitor C1.

[0010] As a further improvement of the above technical solution, the proportional valve control module also includes an NPN transistor Q3, a diode D1, a resistor R5, a resistor R6, a capacitor C2 and a capacitor C3. The output end of the operational amplifier U1 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected to the ground, the collector of the transistor Q3 is connected to the gate of the switch tube Q1 through the resistor R5, and the gate of the switch tube Q1 is connected to the power module through the resistor R6. The capacitor C3 is connected in parallel with the resistor R6, and the two ends of the capacitor C2 are connected one-to-one to the two proportional valve ports. The cathode of the diode D1 is connected to the drain of the switch tube Q1, and the anode of the diode D1 is connected to the ground.

[0011] As a further improvement of the above technical solution, the pulse discharge module includes a PNP transistor Q4, an NPN transistor Q5, a resistor R7, a resistor R8, a resistor R9, a capacitor C4, a capacitor C5, a diode D2, a discharge tube U2, a mutual inductor L1 and a mutual inductor L2, the mutual inductor L1 is configured with a winding L1-1, a winding L1-2 and a winding L1-3, and the mutual inductor L2 is configured with a winding L2-1 and a winding L2-2;

[0012] The microcontroller is connected to the base of the transistor Q4, the emitter of the transistor Q4 is connected to the power module, the collector of the transistor Q4 is connected to one end of the resistor R8 and one end of the winding L1-1 through the resistor R7, the other end of the resistor R8 is connected to the emitter of the transistor Q4 and one end of the winding L1-2, the other end of the winding L1-1 is connected to the base of the transistor Q5, the other end of the winding L1-2 is connected to the collector of the transistor Q5, the emitter of the transistor Q5 is connected to the ground, and the two ends of the capacitor C4 are connected to the transistors. The base and emitter of Q5 are connected, one end of the winding L1-3 is connected to the anode of the diode D2, the other end of the winding L1-3 is connected to the ground, the cathode of the diode D2 is connected to one end of the discharge tube U2, the other end of the discharge tube U2 is connected to the ground, the resistor R9 is connected in parallel with the discharge tube U2, one end of the capacitor C5 is connected to the cathode of the diode D2, the other end of the capacitor C5 is connected to one end of the winding L2-1, the other end of the winding L2-1 is connected to the ground, the winding L2-2 is configured with a center tap, and the center tap of the winding L2-2 is connected to the ground.

[0013] As a further improvement of the above technical solution, the flame detection module includes capacitor C6, capacitor C7, capacitor C8, capacitor C9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, diode D3, diode D4 and flame detection needle;

[0014] The positive electrode of the diode D2 is connected to the flame detection needle through the capacitor C6, the resistor R10 and the resistor R16 in sequence. One end of the resistor R11 is connected to the connection point of the resistor R10 and the resistor R16, and the other end of the resistor R11 is connected to the ground through the capacitor C7. One end of the resistor R12 is connected to the connection point of the resistor R11 and the capacitor C7, and the other end of the resistor R12 is connected to the negative electrode of the diode D4. The positive electrode of the diode D4 is connected to the ground. The positive electrode of the diode D3 is connected to the negative electrode of the diode D4, and the negative electrode of the diode D3 is connected to the power module. One end of the resistor R13 is connected to the positive electrode of the diode D3, and the other end of the resistor R13 is connected to the microcontroller through the resistor R14 and to the ground through the capacitor C8. One end of the resistor R15 is connected to the connection point of the resistor R13 and the resistor R14, and the other end of the resistor R15 is connected to the power module and to the ground through the capacitor C9.

[0015] As a further improvement of the above technical solution, the power module includes a power supply port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C10, a capacitor C11, a capacitor C12, a diode D5, a diode D6, an NPN transistor Q6 and a switch tube Q7;

[0016] The microcontroller is connected to the cathode of the diode D5 via the resistor R17 and the capacitor C10, the anode of the diode D5 is connected to the ground, the anode of the diode D6 is connected to the cathode of the diode D5, the cathode of the diode D6 is connected to the ground via the capacitor C11, one end of the resistor R18 is connected to the cathode of the diode D6, the other end of the resistor R18 is connected to the ground via the resistor R19 and is connected to the base of the transistor Q6, and the emitter of the transistor Q6 is connected to the cathode of the diode D6. The collector of the transistor Q6 is connected to the gate of the switch tube Q7 through the resistor R20, the source of the switch tube Q7 is connected to the power supply port, the drain of the switch tube Q7 is connected to the ground through the resistor R22, the drain of the switch tube Q7 is connected to the microcontroller, the two ends of the resistor R21 are respectively connected to the gate and source of the switch tube Q7, the capacitor C12 is connected in parallel with the resistor R21, and the drain of the switch tube Q7 serves as the power supply port for the power module to provide external power.

[0017] As a further improvement of the above technical solution, the present technical solution further includes a temperature detection module, the power supply module is connected to the temperature detection module, and the temperature detection module is connected to the microcontroller.

[0018] As a further improvement of the above technical solution, the present technical solution further includes a communication module, the power module is connected to the communication module, and the microcontroller is connected to the communication module.

[0019] The beneficial effects of the present invention are as follows: the resistor R1 in the proportional valve control module of the present technical solution is used to collect the proportional valve coil current, the voltage regulating unit is used to control the output voltage amplitude according to the duty cycle of the PWM signal output by the microcontroller, and the operational amplifier U1 controls the on and off of the switch tube Q1 according to the voltage signal transmitted by the voltage regulating unit and the resistor R1, thereby realizing the closed-loop control function of the proportional valve and improving the stability of the water flow in the gas water heater pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 It is a circuit module framework diagram of the present invention;

[0022] Figure 2 is a circuit schematic diagram of the proportional valve control module of the present invention;

[0023] Figure 3 This is a circuit diagram of the pulse discharge module and the flame detection module of the present invention;

[0024] Figure 4 It is a circuit principle diagram of the power module of the present invention. DETAILED DESCRIPTION

[0025] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0027] In the description of the present invention, the meaning of "several" is one or more, the meaning of "many" is more than two, and the meanings of "greater than", "less than", "exceed" and "exceed" are not inclusive of the number itself, while the meanings of "above", "below", "within" and "include" are inclusive of the number itself. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features. In the description of the present invention, unless otherwise clearly defined, the terms "set", "install", "connect" and "connect" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0028] Reference Figures 1 to 4 , the present application discloses a gas water heater control circuit, a first embodiment of which includes a power supply module, a flow detection module, a self-priming valve control module, a pulse discharge module, a flame detection module, a proportional valve control module and a microcontroller;

[0029] The power supply module is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module, the proportional valve control module and the microcontroller, and the microcontroller is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module and the proportional valve control module;

[0030] The proportional valve control module includes a proportional valve port, an operational amplifier U1, a switch tube Q1, a resistor R1 and a voltage regulating unit. The proportional valve ports are configured with two, the microcontroller is connected to the voltage regulating unit, and the voltage regulating unit is configured to control the voltage amplitude of its output according to the duty cycle of the PWM signal output by the microcontroller. The voltage regulating unit is connected to the non-inverting input terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the gate of the switch tube Q1, the source of the switch tube Q1 is connected to the power module, the drain of the switch tube Q1 is connected to one of the proportional valve ports, and the other proportional valve port is connected to the inverting input terminal of the operational amplifier U1, and is connected to the ground terminal through the resistor R1.

[0031] Specifically, the proportional valve control module in this embodiment is used to be connected to a proportional valve that controls the water flow in the gas water heater pipeline. The resistor R1 in the proportional valve control module is used to collect the proportional valve coil current. The voltage regulating unit is used to control the output voltage amplitude according to the duty cycle of the PWM signal output by the microcontroller. The operational amplifier U1 controls the on and off of the switch tube Q1 according to the voltage signal transmitted by the voltage regulating unit and the resistor R1, thereby realizing the closed-loop control function of the proportional valve and improving the stability of the water flow in the gas water heater pipeline.

[0032] As a further preferred embodiment, in this embodiment, the voltage regulating unit includes an NPN transistor Q2, a resistor R2, a resistor R3, a resistor R4, and a capacitor C1. The microcontroller is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the ground, the resistors R2 and R3 are connected in series between the power module and the ground, the collector of the transistor Q2 is connected to the connection point between the resistors R2 and R3, one end of the resistor R4 is connected to the collector of the transistor Q2, and the other end of the resistor R4 is connected to the ground via the capacitor C1. The non-inverting input of the operational amplifier U1 is connected to the connection point between the resistor R4 and the capacitor C1. In this embodiment, the resistors R2 and R3 are used for voltage division. The transistor Q2 is continuously turned on and off according to the PWM signal output by the microcontroller. The different duty cycles of the PWM signal output by the microcontroller result in different potentials at the connection point between the resistors R2 and R3. The resistor R4 and the capacitor C1 form an integrating circuit for voltage stabilization.

[0033] As a further preferred embodiment, in this embodiment, the proportional valve control module further includes an NPN transistor Q3, a diode D1, a resistor R5, a resistor R6, a capacitor C2, and a capacitor C3. The output end of the operational amplifier U1 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected to the ground, the collector of the transistor Q3 is connected to the gate of the switch tube Q1 via the resistor R5, and the gate of the switch tube Q1 is connected to the power module via the resistor R6. The capacitor C3 is connected in parallel with the resistor R6. The two ends of the capacitor C2 are connected to the two proportional valve ports in a one-to-one correspondence. The cathode of the diode D1 is connected to the drain of the switch tube Q1, and the anode of the diode D1 is connected to the ground. In this embodiment, the connection circuit of the transistor Q3, the resistor R5, the resistor R6, and the capacitor C3 is used to improve the microcontroller's ability to drive the switch tube Q1.

[0034] As a further preferred embodiment, in this embodiment, the pulse discharge module includes a PNP transistor Q4, an NPN transistor Q5, a resistor R7, a resistor R8, a resistor R9, a capacitor C4, a capacitor C5, a diode D2, a discharge tube U2, a mutual inductor L1, and a mutual inductor L2. The mutual inductor L1 is configured with a winding L1-1, a winding L1-2, and a winding L1-3. The mutual inductor L2 is configured with a winding L2-1 and a winding L2-2.

[0035] The microcontroller is connected to the base of the transistor Q4, the emitter of the transistor Q4 is connected to the power module, the collector of the transistor Q4 is connected to one end of the resistor R8 and one end of the winding L1-1 through the resistor R7, the other end of the resistor R8 is connected to the emitter of the transistor Q4 and one end of the winding L1-2, the other end of the winding L1-1 is connected to the base of the transistor Q5, the other end of the winding L1-2 is connected to the collector of the transistor Q5, the emitter of the transistor Q5 is connected to the ground, and the two ends of the capacitor C4 are connected to the transistors. The base and emitter of Q5 are connected, one end of the winding L1-3 is connected to the anode of the diode D2, the other end of the winding L1-3 is connected to the ground, the cathode of the diode D2 is connected to one end of the discharge tube U2, the other end of the discharge tube U2 is connected to the ground, the resistor R9 is connected in parallel with the discharge tube U2, one end of the capacitor C5 is connected to the cathode of the diode D2, the other end of the capacitor C5 is connected to one end of the winding L2-1, the other end of the winding L2-1 is connected to the ground, the winding L2-2 is configured with a center tap, and the center tap of the winding L2-2 is connected to the ground.

[0036] Specifically, in this embodiment, when the microcontroller transmits a low level to the base of the transistor Q4, the transistor Q4 and the transistor Q5 are both turned on, and the circuit oscillates. The voltage is boosted by the transformer L1, and then the capacitor C5 is charged. When the capacitor C5 reaches the breakdown voltage of the discharge tube U2, the discharge tube U2 is turned on, and its discharge current passes through the transformer L2 to generate a high-amplitude pulse voltage in the winding L2-2 to generate a discharge spark between the ignition pin gaps.

[0037] As a further preferred embodiment, in this embodiment, the flame detection module includes capacitor C6, capacitor C7, capacitor C8, capacitor C9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, diode D3, diode D4 and flame detection needle;

[0038] The positive electrode of the diode D2 is connected to the flame detection needle through the capacitor C6, the resistor R10 and the resistor R16 in sequence. One end of the resistor R11 is connected to the connection point of the resistor R10 and the resistor R16, and the other end of the resistor R11 is connected to the ground through the capacitor C7. One end of the resistor R12 is connected to the connection point of the resistor R11 and the capacitor C7, and the other end of the resistor R12 is connected to the negative electrode of the diode D4. The positive electrode of the diode D4 is connected to the ground. The positive electrode of the diode D3 is connected to the negative electrode of the diode D4, and the negative electrode of the diode D3 is connected to the power module. One end of the resistor R13 is connected to the positive electrode of the diode D3, and the other end of the resistor R13 is connected to the microcontroller through the resistor R14 and to the ground through the capacitor C8. One end of the resistor R15 is connected to the connection point of the resistor R13 and the resistor R14, and the other end of the resistor R15 is connected to the power module and to the ground through the capacitor C9.

[0039] Specifically, in this embodiment, when the microcontroller transmits a high level to the base of the transistor Q4, the transistor Q4 is cut off, the pulse discharge module maintains a weak oscillation, and generates a low-amplitude AC voltage to be transmitted to the flame detection needle. Since the flame has unidirectional conductivity, the positive charge flows into the ground through the flame, and the negative charge is transmitted to the microcontroller for detection through the resistor R11, the resistor R12, the resistor R13 and the resistor R14. When the microcontroller detects the flame signal, it stops ignition and keeps the gas valve open to supply gas to the water heater combustion chamber to maintain combustion.

[0040] As a further preferred embodiment, in this embodiment, the power module includes a power supply port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C10, a capacitor C11, a capacitor C12, a diode D5, a diode D6, an NPN transistor Q6, and a switch tube Q7;

[0041] The microcontroller is connected to the cathode of the diode D5 via the resistor R17 and the capacitor C10, the anode of the diode D5 is connected to the ground, the anode of the diode D6 is connected to the cathode of the diode D5, the cathode of the diode D6 is connected to the ground via the capacitor C11, one end of the resistor R18 is connected to the cathode of the diode D6, the other end of the resistor R18 is connected to the ground via the resistor R19 and is connected to the base of the transistor Q6, and the emitter of the transistor Q6 is connected to the cathode of the diode D6. The collector of the transistor Q6 is connected to the gate of the switch tube Q7 through the resistor R20, the source of the switch tube Q7 is connected to the power supply port, the drain of the switch tube Q7 is connected to the ground through the resistor R22, the drain of the switch tube Q7 is connected to the microcontroller, the two ends of the resistor R21 are respectively connected to the gate and source of the switch tube Q7, the capacitor C12 is connected in parallel with the resistor R21, and the drain of the switch tube Q7 serves as the power supply port for the power module to provide external power.

[0042] Specifically, in this embodiment, when the capacitor C10 is a DC blocking capacitor, only AC pulse signals can flow through, which prevents the microcontroller from freezing or being damaged and causes the transistor Q6 and the switch tube Q7 to be directly turned on, thereby meeting the safety level requirements.

[0043] As a further preferred implementation, this embodiment further includes a temperature detection module, the power module is connected to the temperature detection module, and the temperature detection module is connected to the microcontroller.

[0044] As a further preferred embodiment, this embodiment further includes a communication module, the power module being connected to the communication module, and the microcontroller being connected to the communication module. In this embodiment, the communication module is preferably configured as a wired communication module, such as a USB communication module, and is used to implement a communication connection function with an external device.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A gas water heater control circuit, characterized in that: It includes a power supply module, a flow detection module, a self-priming valve control module, a pulse discharge module, a flame detection module, a proportional valve control module and a microcontroller; The power supply module is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module, the proportional valve control module and the microcontroller, and the microcontroller is respectively connected to the flow detection module, the self-priming valve control module, the pulse discharge module, the flame detection module and the proportional valve control module; The proportional valve control module includes a proportional valve port, an operational amplifier U1, a switch tube Q1, a resistor R1, and a voltage regulating unit. The proportional valve ports are configured with two, the microcontroller is connected to the voltage regulating unit, the voltage regulating unit is connected to the non-inverting input terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the gate of the switch tube Q1, the source of the switch tube Q1 is connected to the power module, the drain of the switch tube Q1 is connected to one of the proportional valve ports, and the other proportional valve port is connected to the inverting input terminal of the operational amplifier U1 and is connected to the ground terminal through the resistor R1; The proportional valve control module is used to be connected to the proportional valve that controls the water flow in the gas water heater pipeline. The resistor R1 in the proportional valve control module is used to collect the current of the proportional valve coil. The voltage regulating unit is used to control the output voltage amplitude according to the duty cycle of the PWM signal output by the microcontroller. The operational amplifier U1 controls the on and off of the switch tube Q1 according to the voltage signal transmitted by the voltage regulating unit and the resistor R1.

2. A gas water heater control circuit according to claim 1, characterized in that: The voltage regulating unit includes a transistor Q2, a resistor R2, a resistor R3, a resistor R4 and a capacitor C1. The microcontroller is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the ground, the resistor R2 and the resistor R3 are connected in series between the power module and the ground, the collector of the transistor Q2 is connected to the connection point of the resistor R2 and the resistor R3, one end of the resistor R4 is connected to the collector of the transistor Q2, and the other end of the resistor R4 is connected to the ground through the capacitor C1. The non-inverting input of the operational amplifier U1 is connected to the connection point of the resistor R4 and the capacitor C1.

3. A gas water heater control circuit according to claim 2, characterized in that: The proportional valve control module also includes a transistor Q3, a diode D1, a resistor R5, a resistor R6, a capacitor C2 and a capacitor C3. The output end of the operational amplifier U1 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected to the ground, the collector of the transistor Q3 is connected to the gate of the switch tube Q1 through the resistor R5, the gate of the switch tube Q1 is connected to the power module through the resistor R6, the capacitor C3 is connected in parallel with the resistor R6, the two ends of the capacitor C2 are connected to the two proportional valve ports in a one-to-one correspondence, the cathode of the diode D1 is connected to the drain of the switch tube Q1, and the anode of the diode D1 is connected to the ground.

4. A gas water heater control circuit according to claim 1, characterized in that: The pulse discharge module includes a transistor Q4, a transistor Q5, a resistor R7, a resistor R8, a resistor R9, a capacitor C4, a capacitor C5, a diode D2, a discharge tube U2, a mutual inductor L1 and a mutual inductor L2. The mutual inductor L1 is configured with a winding L1-1, a winding L1-2 and a winding L1-3. The mutual inductor L2 is configured with a winding L2-1 and a winding L2-2. The microcontroller is connected to the base of the transistor Q4, the emitter of the transistor Q4 is connected to the power module, the collector of the transistor Q4 is connected to one end of the resistor R8 and one end of the winding L1-1 through the resistor R7, the other end of the resistor R8 is connected to the emitter of the transistor Q4 and one end of the winding L1-2, the other end of the winding L1-1 is connected to the base of the transistor Q5, the other end of the winding L1-2 is connected to the collector of the transistor Q5, the emitter of the transistor Q5 is connected to the ground, and the two ends of the capacitor C4 are connected to the transistors. The base and emitter of Q5 are connected, one end of the winding L1-3 is connected to the anode of the diode D2, the other end of the winding L1-3 is connected to the ground, the cathode of the diode D2 is connected to one end of the discharge tube U2, the other end of the discharge tube U2 is connected to the ground, the resistor R9 is connected in parallel with the discharge tube U2, one end of the capacitor C5 is connected to the cathode of the diode D2, the other end of the capacitor C5 is connected to one end of the winding L2-1, the other end of the winding L2-1 is connected to the ground, the winding L2-2 is configured with a center tap, and the center tap of the winding L2-2 is connected to the ground.

5. A gas water heater control circuit according to claim 4, characterized in that: The flame detection module includes capacitor C6, capacitor C7, capacitor C8, capacitor C9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, diode D3, diode D4 and flame detection needle; The positive electrode of the diode D2 is connected to the flame detection needle through the capacitor C6, the resistor R10 and the resistor R16 in sequence. One end of the resistor R11 is connected to the connection point of the resistor R10 and the resistor R16, and the other end of the resistor R11 is connected to the ground through the capacitor C7. One end of the resistor R12 is connected to the connection point of the resistor R11 and the capacitor C7, and the other end of the resistor R12 is connected to the negative electrode of the diode D4. The positive electrode of the diode D4 is connected to the ground. The positive electrode of the diode D3 is connected to the negative electrode of the diode D4, and the negative electrode of the diode D3 is connected to the power module. One end of the resistor R13 is connected to the positive electrode of the diode D3, and the other end of the resistor R13 is connected to the microcontroller through the resistor R14 and to the ground through the capacitor C8. One end of the resistor R15 is connected to the connection point of the resistor R13 and the resistor R14, and the other end of the resistor R15 is connected to the power module and to the ground through the capacitor C9.

6. A gas water heater control circuit according to claim 1, characterized in that: The power supply module includes a power supply port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a capacitor C10, a capacitor C11, a capacitor C12, a diode D5, a diode D6, a transistor Q6 and a switch tube Q7; The microcontroller is connected to the cathode of the diode D5 via the resistor R17 and the capacitor C10 in sequence. The anode of the diode D5 is connected to the ground. The anode of the diode D6 is connected to the cathode of the diode D5. The cathode of the diode D6 is connected to the ground via the capacitor C11. One end of the resistor R18 is connected to the cathode of the diode D6. The other end of the resistor R18 is connected to the ground via the resistor R19 and to the base of the transistor Q6. The emitter of the transistor Q6 is connected to the ground. The collector of the transistor Q6 is connected to the gate of the switch tube Q7 via the resistor R20. The source of the switch tube Q7 is connected to the power supply port. The drain of the switch tube Q7 is connected to the ground via the resistor R22. The drain of the switch tube Q7 is connected to the microcontroller. Two ends of the resistor R21 are respectively connected to the gate and source of the switch tube Q7. The capacitor C12 is connected in parallel with the resistor R21.

7. A gas water heater control circuit according to claim 1, characterized in that: It also includes a temperature detection module, the power supply module is connected to the temperature detection module, and the temperature detection module is connected to the microcontroller.

8. A gas water heater control circuit according to claim 1, characterized in that: It also includes a communication module, the power module is connected to the communication module, and the microcontroller is connected to the communication module.

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