LC resonance voltage and current phase difference detection circuit

Abstract

The invention discloses an LC resonance voltage and current phase difference detection circuit, which comprises a current detection module, a half-bridge driving module, a power supply module and a single chip microcomputer module, and is characterized in that the current detection module comprises a Hall sensor chip, a first filtering unit and a second filtering unit. According to the technical scheme, a current detection module with a Hall sensor chip as a core is used for detecting current parameters output by a half-bridge driving module, and a single-chip microcomputer module calculates the voltage and current phase difference of LC series resonance according to the current parameters and voltage parameters output by the half-bridge driving module; according to the technical scheme, the Hall sensor chip is used for replacing a current transformer, so that the circuit size of the induction cooker is reduced, and the operation loss is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and more specifically to an LC resonance voltage and current phase difference detection circuit. Background Art

[0002] Induction cooker is one of the common household appliances, which mainly converts electrical energy into electromagnetic energy and utilizes eddy current effect to heat metal components. Existing induction cookers are classified into half-bridge type and full-bridge type according to their circuit topology.

[0003] For half-bridge induction cookers, the heating power cannot be adjusted by adjusting the PWM duty cycle, but can only be adjusted by adjusting the PWM frequency. Therefore, in the process of adjusting the frequency, it is necessary to detect the phase relationship between voltage and current in real time to avoid entering the LC series resonance into the capacitive area or the same phase, which may cause overcurrent to break down the switching device. Traditional current phase detection uses constantan wire to pass through the mutual inductor. The mutual inductor induces the resonant current, which is used for the microcontroller to detect and judge as a condition to drive the switching device on and off, resulting in a larger circuit size of the induction cooker and larger operating losses. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide an LC resonant voltage and current phase difference detection circuit.

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

[0006] An LC resonant voltage-current phase difference detection circuit comprises a current detection module, a half-bridge driving module, a power supply module and a single-chip computer module, wherein the power supply module is respectively connected to the current detection module, the half-bridge driving module and the single-chip computer module, the single-chip computer module is connected to the half-bridge driving module, and the current detection module is respectively connected to the half-bridge driving module and the single-chip computer module;

[0007] The current detection module includes a Hall sensor chip, a first filtering unit and a second filtering unit. The Hall sensor chip is configured with a sampling current positive terminal, a sampling current negative terminal, a reference voltage terminal and an output voltage terminal. The sampling current positive terminal and the sampling current negative terminal of the Hall sensor chip are respectively connected to the half-bridge driving module, the output voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the first filtering unit, and the reference voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the second filtering unit.

[0008] As a further improvement of the above technical solution, the model of the Hall sensor chip is CC6905.

[0009] As a further improvement of the above technical solution, the first filtering unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2 and a capacitor C3, the output voltage end of the Hall sensor chip is connected to the ground end through the resistor R1 and the capacitor C1 in sequence, the resistor R2 is connected in parallel with the capacitor C1, the capacitor C2 is connected in parallel with the capacitor C1, one end of the resistor R3 is connected to the connection point between the resistor R1 and the capacitor C1, the other end of the resistor R3 is connected to the ground end through the resistor R4, the capacitor C3 is connected in parallel with the resistor R4, and the single-chip computer module is connected to the connection point between the resistor R3 and the resistor R4;

[0010] The second filtering unit includes a resistor R5, a resistor R6 and a capacitor C4. The reference voltage terminal of the Hall sensor chip is connected to the ground terminal through the resistor R5 and the resistor R6 in sequence. The capacitor C4 is connected in parallel with the resistor R6. The single-chip computer module is connected to the connection point between the resistor R5 and the resistor R6.

[0011] As a further improvement of the above technical solution, the half-bridge driving module includes a first connection end, a second connection end, a half-bridge driving chip, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a diode D1, a diode D2, a diode D3, a diode D4, a switch tube Q1 and a switch tube Q2, and the half-bridge driving chip is configured with a high-side input end, a low-side input end, a high-side output end, a low-side output end, a high-side offset voltage end and a high-side absolute voltage end;

[0012] The single-chip microcomputer module is connected to the high-side input end of the half-bridge driver chip through the resistor R7, the high-side input end of the half-bridge driver chip is connected to the ground end through the resistor R8, the high-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C5, the single-chip microcomputer module is connected to the low-side input end of the half-bridge driver chip through the resistor R9, the low-side input end of the half-bridge driver chip is connected to the ground end through the resistor R10, the low-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C6, and the low-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R14. and the cathode of the diode D3, the anode of the diode D3 and the other end of the resistor R14 are both connected to the cathode of the diode D4, the anode of the diode D4 is connected to the ground, the resistor R15 is connected in parallel with the diode D4, the cathode of the diode D4 is connected to the gate of the switch tube Q1, the emitter of the switch tube Q1 is connected to the ground, the collector of the switch tube Q1 is connected to the first connection end, the two ends of the resistor R16 are connected to the collector and emitter of the switch tube Q1 in a one-to-one correspondence, the capacitor C8 is connected in parallel with the resistor R16, and the half-bridge driver The high-side offset voltage end of the chip is connected to the first connection end, the high-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R11 and the cathode of the diode D1, the anode of the diode D1 and the other end of the resistor R11 are both connected to the cathode of the diode D2, the anode of the diode D2 is connected to the high-side offset voltage end of the half-bridge driver chip, the resistor R12 is connected in parallel with the diode D2, the cathode of the diode D2 is connected to the gate of the switch tube Q2, the emitter of the switch tube Q2 is connected to the high-side offset voltage end of the half-bridge driver chip, and the switch The collector of the switch tube Q2 is connected to the power module, the two ends of the resistor R13 are connected to the emitter and collector of the switch tube Q2 in a one-to-one correspondence, the capacitor C7 is connected in parallel with the resistor R13, the high-side absolute voltage end of the half-bridge drive chip is connected to the high-side offset voltage end of the half-bridge drive chip through the capacitor C9, the capacitor C10 and the capacitor C11 are connected in series between the collector of the switch tube Q2 and the emitter of the switch tube Q1, the second connection end is connected to the current detection module, and the connection point between the capacitor C10 and the capacitor C11 is connected to the current detection module.

[0013] As a further improvement of the above technical solution, the model of the half-bridge driver chip is FD2606.

[0014] As a further improvement of the above technical solution, the circuit further includes a human-computer interaction module, the power supply module is connected to the human-computer interaction module, and the human-computer interaction module is connected to the single-chip computer module.

[0015] The human-computer interaction module includes an access port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a capacitor C12, and a capacitor C13, and the access port is configured with a first communication terminal and a second communication terminal;

[0016] The first communication end of the access port is connected to the single-chip computer module through the resistor R17, one end of the resistor R18 is connected to the connection point between the resistor R17 and the first communication end of the access port, and the other end of the resistor R18 is connected to the ground end, one end of the capacitor C12 is connected to the connection point between the resistor R17 and the single-chip computer module, and the other end of the capacitor C12 is connected to the ground end, the second communication end of the access port is connected to the single-chip computer module through the resistor R19, one end of the resistor R20 is connected to the connection point between the resistor R19 and the second communication end of the access port, and the other end of the resistor R20 is connected to the ground end, one end of the capacitor C13 is connected to the connection point between the resistor R19 and the single-chip computer module, and the other end of the capacitor C13 is connected to the ground end.

[0017] The beneficial effects of the present invention are as follows: in the technical solution, a current detection module using a Hall sensor chip as the core is used to detect the current parameters output by the half-bridge drive module, and the single-chip computer module calculates the voltage and current phase difference of the LC series resonance according to the current parameters and voltage parameters output by the half-bridge drive module; the technical solution uses a Hall sensor chip to replace the current transformer, thereby reducing the volume of the induction cooker circuit and also effectively reducing the operating loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0019] Figure 1 It is a circuit module framework diagram of the present invention;

[0020] Figure 2 is a circuit schematic diagram of the current detection module of the present invention;

[0021] Figure 3 is a circuit schematic diagram of a half-bridge driving module of the present invention;

[0022] Figure 4 It is a circuit principle diagram of the human-computer interaction module of the present invention. DETAILED DESCRIPTION

[0023] 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 cannot be understood as a limitation on the scope of protection of the present invention.

[0024] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, 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, and therefore should not be understood as a limitation on the present invention.

[0025] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used 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.

[0026] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0027] Reference Figures 1 to 4 The present application discloses an LC resonant voltage-current phase difference detection circuit, a first embodiment of which includes a current detection module, a half-bridge driving module, a power supply module and a single-chip computer module, wherein the power supply module outputs 310V DC voltage, 15V DC voltage and 5V DC voltage to the outside, the power supply module is respectively connected to the current detection module, the half-bridge driving module and the single-chip computer module, the single-chip computer module is connected to the half-bridge driving module, and the current detection module is respectively connected to the half-bridge driving module and the single-chip computer module;

[0028] The current detection module includes a Hall sensor chip, a first filtering unit and a second filtering unit. The Hall sensor chip is configured with a sampling current positive terminal, a sampling current negative terminal, a reference voltage terminal and an output voltage terminal. The sampling current positive terminal and the sampling current negative terminal of the Hall sensor chip are respectively connected to the half-bridge driving module, the output voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the first filtering unit, and the reference voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the second filtering unit.

[0029] Specifically, in this embodiment, the current detection module with the Hall sensor chip as the core detects the current parameters output by the half-bridge driving module, and the single-chip computer module calculates the voltage and current phase difference of the LC series resonance according to the current parameters and voltage parameters output by the half-bridge driving module; in this embodiment, the Hall sensor chip is used to replace the current transformer, so as to reduce the volume of the induction cooker circuit and effectively reduce the operating loss.

[0030] As a further preferred implementation, in this embodiment, the model of the Hall sensor chip is CC6905. This model of the Hall sensor chip consists of a high-precision, low-noise linear Hall integrated circuit and a low-impedance main current conductor, and is manufactured using advanced BiCMOS technology. It internally includes a differential Hall sensor, a chopper amplifier, a variable gain amplifier, output polarity / sensitivity / offset, an oscillator, a filter, a zero reference output, an overcurrent output, and an amplifier buffer output, etc. This model of the Hall sensor chip adopts linear Hall sensor temperature compensation technology and has high temperature stability. Its internally integrated differential common-mode suppression circuit can prevent the chip output from being affected by external interference magnetic signals, and the integrated dynamic offset elimination circuit prevents the chip sensitivity from being affected by external pressure and chip packaging stress.

[0031] Further as a preferred implementation, in this embodiment, the first filtering unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2 and a capacitor C3, the output voltage end of the Hall sensor chip is connected to the ground end through the resistor R1 and the capacitor C1 successively, the resistor R2 is connected in parallel with the capacitor C1, the capacitor C2 is connected in parallel with the capacitor C1, one end of the resistor R3 is connected to the connection point between the resistor R1 and the capacitor C1, the other end of the resistor R3 is connected to the ground end through the resistor R4, the capacitor C3 is connected in parallel with the resistor R4, and the single-chip computer module is connected to the connection point between the resistor R3 and the resistor R4;

[0032] The second filtering unit includes a resistor R5, a resistor R6 and a capacitor C4. The reference voltage terminal of the Hall sensor chip is connected to the ground terminal through the resistor R5 and the resistor R6 in sequence. The capacitor C4 is connected in parallel with the resistor R6. The single-chip computer module is connected to the connection point between the resistor R5 and the resistor R6.

[0033] Specifically, in this embodiment, the first filtering unit performs voltage division filtering processing on the voltage signal output by the output voltage end of the Hall sensor chip, and the second filtering unit performs voltage division filtering processing on the voltage signal output by the reference voltage end of the Hall sensor chip, so as to improve the detection accuracy of the single-chip computer module on the voltage signals output by the output voltage end and the reference voltage end of the Hall sensor chip.

[0034] As a further preferred implementation, in the present embodiment, the half-bridge driving module includes a first connection end, a second connection end, a half-bridge driving chip, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a diode D1, a diode D2, a diode D3, a diode D4, a switch tube Q1 and a switch tube Q2, and the half-bridge driving chip is configured with a high-side input end, a low-side input end, a high-side output end, a low-side output end, a high-side offset voltage end and a high-side absolute voltage end;

[0035] The single-chip microcomputer module is connected to the high-side input end of the half-bridge driver chip through the resistor R7, the high-side input end of the half-bridge driver chip is connected to the ground end through the resistor R8, the high-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C5, the single-chip microcomputer module is connected to the low-side input end of the half-bridge driver chip through the resistor R9, the low-side input end of the half-bridge driver chip is connected to the ground end through the resistor R10, and the low-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C6.

[0036] The low-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R14 and the cathode of the diode D3, the anode of the diode D3 and the other end of the resistor R14 are both connected to the cathode of the diode D4, the anode of the diode D4 is connected to the ground, the resistor R15 is connected in parallel with the diode D4, the cathode of the diode D4 is connected to the gate of the switch tube Q1, the emitter of the switch tube Q1 is connected to the ground, the collector of the switch tube Q1 is connected to the first connection end, the two ends of the resistor R16 are connected one-to-one with the collector and emitter of the switch tube Q1, the capacitor C8 is connected in parallel with the resistor R16, the high-side offset voltage end of the half-bridge driver chip is connected to the first connection end, the high-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R11 and the cathode of the diode D1, the anode of the diode D1 and the other end of the resistor R11 are both connected to the The cathode of the diode D2 is connected, the anode of the diode D2 is connected to the high-side offset voltage end of the half-bridge driver chip, the resistor R12 is connected in parallel with the diode D2, the cathode of the diode D2 is connected to the gate of the switch tube Q2, the emitter of the switch tube Q2 is connected to the high-side offset voltage end of the half-bridge driver chip, the collector of the switch tube Q2 is connected to the power module, the two ends of the resistor R13 are connected one-to-one with the emitter and collector of the switch tube Q2, the capacitor C7 is connected in parallel with the resistor R13, the high-side absolute voltage end of the half-bridge driver chip is connected to the high-side offset voltage end of the half-bridge driver chip through the capacitor C9, the capacitor C10 and the capacitor C11 are connected in series between the collector of the switch tube Q2 and the emitter of the switch tube Q1, the second connection end is connected to the current detection module, and the connection point between the capacitor C10 and the capacitor C11 is connected to the current detection module.

[0037] As a further preferred implementation, in this embodiment, the model of the half-bridge driver chip is FD2606. This model of half-bridge driver chip has built-in VCC and VB undervoltage protection functions to prevent the power tube from operating at too low a voltage. Its logic input is compatible with both TTL and CMOS types, which is convenient for interfacing with control devices. The chip output of this model has a high pulse current buffer design with minimum driver transconductance.

[0038] As a further preferred implementation, this embodiment further includes a human-computer interaction module, the power module is connected to the human-computer interaction module, and the human-computer interaction module is connected to the single-chip computer module.

[0039] Preferably, in this embodiment, the human-computer interaction module includes an access port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a capacitor C12, and a capacitor C13, and the access port is configured with a first communication terminal and a second communication terminal;

[0040] The first communication end of the access port is connected to the single-chip computer module through the resistor R17, one end of the resistor R18 is connected to the connection point between the resistor R17 and the first communication end of the access port, and the other end of the resistor R18 is connected to the ground end, one end of the capacitor C12 is connected to the connection point between the resistor R17 and the single-chip computer module, and the other end of the capacitor C12 is connected to the ground end, the second communication end of the access port is connected to the single-chip computer module through the resistor R19, one end of the resistor R20 is connected to the connection point between the resistor R19 and the second communication end of the access port, and the other end of the resistor R20 is connected to the ground end, one end of the capacitor C13 is connected to the connection point between the resistor R19 and the single-chip computer module, and the other end of the capacitor C13 is connected to the ground end.

[0041] 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 changes made using the contents of the present invention's specification 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. An LC resonant voltage and current phase difference detection circuit, characterized in that: It includes a current detection module, a half-bridge driving module, a power module and a single-chip computer module, wherein the power module is respectively connected to the current detection module, the half-bridge driving module and the single-chip computer module, the single-chip computer module is connected to the half-bridge driving module, and the current detection module is respectively connected to the half-bridge driving module and the single-chip computer module; The current detection module includes a Hall sensor chip, a first filtering unit and a second filtering unit. The Hall sensor chip is configured with a sampling current positive terminal, a sampling current negative terminal, a reference voltage terminal and an output voltage terminal. The sampling current positive terminal and the sampling current negative terminal of the Hall sensor chip are respectively connected to the half-bridge driving module, the output voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the first filtering unit, and the reference voltage terminal of the Hall sensor chip is connected to the single-chip computer module through the second filtering unit.

2. The LC resonant voltage and current phase difference detection circuit according to claim 1, characterized in that: The model of the Hall sensor chip is CC6905.

3. The LC resonant voltage and current phase difference detection circuit according to claim 2, characterized in that: The first filtering unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2 and a capacitor C3, the output voltage end of the Hall sensor chip is connected to the ground end through the resistor R1 and the capacitor C1 in sequence, the resistor R2 is connected in parallel with the capacitor C1, the capacitor C2 is connected in parallel with the capacitor C1, one end of the resistor R3 is connected to the connection point between the resistor R1 and the capacitor C1, the other end of the resistor R3 is connected to the ground end through the resistor R4, the capacitor C3 is connected in parallel with the resistor R4, and the single-chip computer module is connected to the connection point between the resistor R3 and the resistor R4; The second filtering unit includes a resistor R5, a resistor R6 and a capacitor C4. The reference voltage terminal of the Hall sensor chip is connected to the ground terminal through the resistor R5 and the resistor R6 in sequence. The capacitor C4 is connected in parallel with the resistor R6. The single-chip computer module is connected to the connection point between the resistor R5 and the resistor R6.

4. The LC resonant voltage and current phase difference detection circuit according to claim 1, characterized in that: The half-bridge driving module includes a first connection end, a second connection end, a half-bridge driving chip, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a diode D1, a diode D2, a diode D3, a diode D4, a switch tube Q1 and a switch tube Q2, and the half-bridge driving chip is configured with a high-side input end, a low-side input end, a high-side output end, a low-side output end, a high-side offset voltage end and a high-side absolute voltage end; The single-chip microcomputer module is connected to the high-side input end of the half-bridge driver chip through the resistor R7, the high-side input end of the half-bridge driver chip is connected to the ground end through the resistor R8, the high-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C5, the single-chip microcomputer module is connected to the low-side input end of the half-bridge driver chip through the resistor R9, the low-side input end of the half-bridge driver chip is connected to the ground end through the resistor R10, the low-side input end of the half-bridge driver chip is connected to the ground end through the capacitor C6, and the low-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R14. and the cathode of the diode D3, the anode of the diode D3 and the other end of the resistor R14 are both connected to the cathode of the diode D4, the anode of the diode D4 is connected to the ground, the resistor R15 is connected in parallel with the diode D4, the cathode of the diode D4 is connected to the gate of the switch tube Q1, the emitter of the switch tube Q1 is connected to the ground, the collector of the switch tube Q1 is connected to the first connection end, the two ends of the resistor R16 are connected to the collector and emitter of the switch tube Q1 in a one-to-one correspondence, the capacitor C8 is connected in parallel with the resistor R16, and the half-bridge driver The high-side offset voltage end of the chip is connected to the first connection end, the high-side output end of the half-bridge driver chip is respectively connected to one end of the resistor R11 and the cathode of the diode D1, the anode of the diode D1 and the other end of the resistor R11 are both connected to the cathode of the diode D2, the anode of the diode D2 is connected to the high-side offset voltage end of the half-bridge driver chip, the resistor R12 is connected in parallel with the diode D2, the cathode of the diode D2 is connected to the gate of the switch tube Q2, the emitter of the switch tube Q2 is connected to the high-side offset voltage end of the half-bridge driver chip, and the switch The collector of the switch tube Q2 is connected to the power module, the two ends of the resistor R13 are connected to the emitter and collector of the switch tube Q2 in a one-to-one correspondence, the capacitor C7 is connected in parallel with the resistor R13, the high-side absolute voltage end of the half-bridge drive chip is connected to the high-side offset voltage end of the half-bridge drive chip through the capacitor C9, the capacitor C10 and the capacitor C11 are connected in series between the collector of the switch tube Q2 and the emitter of the switch tube Q1, the second connection end is connected to the current detection module, and the connection point between the capacitor C10 and the capacitor C11 is connected to the current detection module.

5. The LC resonant voltage and current phase difference detection circuit according to claim 4, characterized in that: The model of the half-bridge driver chip is FD2606.

6. The LC resonant voltage and current phase difference detection circuit according to claim 1, characterized in that: It also includes a human-computer interaction module, the power module is connected to the human-computer interaction module, and the human-computer interaction module is connected to the single-chip computer module.

7. The LC resonant voltage and current phase difference detection circuit according to claim 6, characterized in that: The human-computer interaction module includes an access port, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a capacitor C12, and a capacitor C13, and the access port is configured with a first communication terminal and a second communication terminal; The first communication end of the access port is connected to the single-chip computer module through the resistor R17, one end of the resistor R18 is connected to the connection point between the resistor R17 and the first communication end of the access port, and the other end of the resistor R18 is connected to the ground end, one end of the capacitor C12 is connected to the connection point between the resistor R17 and the single-chip computer module, and the other end of the capacitor C12 is connected to the ground end, the second communication end of the access port is connected to the single-chip computer module through the resistor R19, one end of the resistor R20 is connected to the connection point between the resistor R19 and the second communication end of the access port, and the other end of the resistor R20 is connected to the ground end, one end of the capacitor C13 is connected to the connection point between the resistor R19 and the single-chip computer module, and the other end of the capacitor C13 is connected to the ground end.

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