A self-regulating controller for electric valve

Abstract

The utility model is an electric valve self-regulating controller, comprising: a power module, an AD module, a microcontroller, a valve feedback circuit, a valve actuator, a solenoid valve drive circuit, a button module, a display module, a PROFIBUS interface, an RS232 serial port and a wireless communication module; the power module is unidirectionally connected to the microcontroller, the AD module is unidirectionally connected to the microcontroller; the microcontroller is bidirectionally connected to the PROFIBUS interface, the microcontroller is bidirectionally connected to the RS232 serial port, the microcontroller is bidirectionally connected to the wireless communication module; the microcontroller is unidirectionally connected to the solenoid valve drive circuit, the microcontroller is unidirectionally connected to the button module, the microcontroller is unidirectionally connected to the display module; the solenoid valve drive circuit is unidirectionally connected to the valve actuator, the valve actuator is unidirectionally connected to the valve feedback circuit, and the valve feedback circuit is unidirectionally connected to the AD module. The utility model adopts microprocessor technology and functional modules, and has the characteristics of self-calibration, self-adaptation, self-diagnosis and maintenance-free operation.

Description

Technical Field

[0001] The utility model relates to the field of valve controllers, in particular to a self-regulating controller for an electric valve. Background Art

[0002] A valve is a mechanical device that controls the flow rate, direction, pressure, temperature, etc. of a flowing fluid medium. A valve is a basic component in a pipeline system. A valve controller is a product used in conjunction with a valve electric device to control the opening and closing of an electric valve, and can achieve remote control of the electric valve in the control room.

[0003] Valve positioner is an auxiliary instrument used in conjunction with a regulating valve to change the flow of fluid. At present, the widely used positioners in China are produced using analog signals and force balance principles. With the continuous development of production process control and the increasing requirements for control performance, traditional positioners can no longer meet the needs of industrial control. Utility Model Content

[0004] In order to overcome the defects of the prior art, the utility model provides an electric valve self-regulating controller, which adopts microprocessor technology and functional modules and has the characteristics of self-calibration, self-adaptation, self-diagnosis and maintenance-free operation.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] An electric valve self-regulating controller, comprising:

[0007] Power module, AD module, microcontroller, valve feedback circuit, valve actuator, solenoid valve drive circuit, key module, display module, PROFIBUS interface, RS232 serial port and wireless communication module;

[0008] The power module is unidirectionally connected to the microcontroller, and the AD module is unidirectionally connected to the microcontroller;

[0009] The microcontroller is bidirectionally connected to the PROFIBUS interface, the microcontroller is bidirectionally connected to the RS232 serial port, and the microcontroller is bidirectionally connected to the wireless communication module;

[0010] The microcontroller is unidirectionally connected to the solenoid valve drive circuit, the microcontroller is unidirectionally connected to the key module, and the microcontroller is unidirectionally connected to the display module;

[0011] The solenoid valve driving circuit is unidirectionally connected to the valve actuator, the valve actuator is unidirectionally connected to the valve feedback circuit, and the valve feedback circuit is unidirectionally connected to the AD module.

[0012] Further, the AD module includes an AD conversion chip U13, pins 1, 2, 3 and 4 of the AD conversion chip U13 are input / output ports, pins 5 and 6 of the AD conversion chip U13 are empty, and pin 7 of the AD conversion chip U13 is grounded;

[0013] Pin 8 of the AD conversion chip U13 is a current detection port, and pin 8 is connected to a first end of a resistor R21, and a second end of the resistor R21 is connected to a +5V voltage;

[0014] Pin 9 of the AD conversion chip U13 is a signal receiving port, pin 10 of the AD conversion chip U13 is a signal sending port, and pin 11 of the AD conversion chip U13 is a clock signal port;

[0015] The pin 12 of the AD conversion chip U13 is connected to the first end of the capacitor C23 and the first end of the capacitor C15 at the same time, and the pin 12 of the AD conversion chip U13 is grounded;

[0016] The second end of the capacitor C23 and the second end of the capacitor C15 are simultaneously connected to the pin 13 of the AD conversion chip U13;

[0017] Pin 14 of the AD conversion chip U13 is simultaneously connected to the first end of the inductor L2, the first end of the capacitor 14, and the first end of the capacitor 22. The second end of the inductor L2 is connected to a +5V voltage. The second end of the capacitor 14 and the second end of the capacitor 22 are simultaneously grounded.

[0018] Further, the valve feedback circuit 4 comprises an instrument amplifier U11, a pin 1 of the instrument amplifier U11 is connected to a first end of a resistor R10, and a second end of the resistor R10 is connected to a pin 8 of the instrument amplifier U11;

[0019] Pin 2 of the instrument amplifier U11 is simultaneously connected to the first end of the capacitor C14, the first end of the capacitor C11, and the first end of the resistor R12, the second end of the capacitor C14 is grounded, and the second end of the resistor R12 is connected to the first end of the potentiometer W1;

[0020] The second end of the capacitor C11 is simultaneously connected to the pin 3 of the instrument amplifier U11, the first end of the capacitor C12, and the first end of the resistor R11, the second end of the capacitor C12 is grounded, and the second end of the resistor R11 is connected to the second end of the potentiometer W1;

[0021] The third end of the potentiometer W1 is a signal source current receiving end, and the third end of the potentiometer W1 is simultaneously connected to the first end of the resistor R14, the anode of the diode D3, and the first end of the resistor R12;

[0022] The second end of the resistor R14 is grounded, and the second end of the resistor R14 is connected to the first end of the resistor R13;

[0023] The fourth end of the potentiometer W1 is simultaneously connected to the second end of the resistor R13, the cathode of the diode D3, the second end of the resistor R12, and the first end of the inductor L2;

[0024] The second end of the inductor L2 is connected to the cathode of the diode D1, and the cathode of the diode D1 is the signal source current receiving end;

[0025] Pin 4 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C13, and a second end of the capacitor C13 is grounded;

[0026] Pin 5 of the instrument amplifier U11 is grounded;

[0027] Pin 6 of the instrument amplifier U11 is simultaneously connected to the anode of the diode D2, the first end of the resistor R15, and the cathode of the diode D4. The cathode of the diode D2 is connected to a +5V voltage. The second end of the resistor R15 is an input / output port. The anode of the diode D4 is connected to a +5V voltage.

[0028] Pin 7 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C9, and a second end of the capacitor C9 is grounded.

[0029] Beneficial effects:

[0030] The utility model discloses an electric valve self-regulating controller, which adopts microprocessor technology and functional modules, has the characteristics of self-calibration, self-adaptation, self-diagnosis and maintenance-free operation, has a simple structure and reasonable design, can realize automatic opening or closing of electromagnetic valves, and is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of an electric valve self-adjusting controller according to an embodiment of the utility model;

[0032] Figure 2 yes Figure 1 The circuit diagram of the AD module;

[0033] Figure 3 yes Figure 1 Schematic diagram of the valve feedback circuit. DETAILED DESCRIPTION

[0034] The principle and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] According to the implementation of the utility model, an electric valve self-regulating controller is proposed, which adopts microprocessor technology and functional modules and has the characteristics of self-calibration, self-adaptation, self-diagnosis and maintenance-free operation.

[0036] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0037] An electric valve self-regulating controller, comprising:

[0038] Power module 1, AD module 2, microcontroller 3, valve feedback circuit 4, valve actuator 5, solenoid valve drive circuit 6, key module 7, display module 8, PROFIBUS interface 9, RS232 serial port 10 and wireless communication module 11;

[0039] The power module 1 is unidirectionally connected to the microcontroller 3, and the AD module 2 is unidirectionally connected to the microcontroller 3;

[0040] The microcontroller 3 is bidirectionally connected to the PROFIBUS interface 9, the microcontroller 3 is bidirectionally connected to the RS232 serial port 10, and the microcontroller 3 is bidirectionally connected to the wireless communication module 11;

[0041] The microcontroller 3 is unidirectionally connected to the solenoid valve driving circuit 6, the microcontroller 3 is unidirectionally connected to the key module 7, and the microcontroller 3 is unidirectionally connected to the display module 8;

[0042] The solenoid valve driving circuit 6 is unidirectionally connected to the valve actuator 5 , the valve actuator 5 is unidirectionally connected to the valve feedback circuit 4 , and the valve feedback circuit 4 is unidirectionally connected to the AD module 2 .

[0043] The AD module includes an AD conversion chip U13, wherein pins 1, 2, 3 and 4 of the AD conversion chip U13 are input / output ports, pins 5 and 6 of the AD conversion chip U13 are left unconnected, and pin 7 of the AD conversion chip U13 is grounded;

[0044] Pin 8 of the AD conversion chip U13 is a current detection port, and pin 8 is connected to a first end of a resistor R21, and a second end of the resistor R21 is connected to a +5V voltage;

[0045] Pin 9 of the AD conversion chip U13 is a signal receiving port, pin 10 of the AD conversion chip U13 is a signal sending port, and pin 11 of the AD conversion chip U13 is a clock signal port;

[0046] The pin 12 of the AD conversion chip U13 is connected to the first end of the capacitor C23 and the first end of the capacitor C15 at the same time, and the pin 12 of the AD conversion chip U13 is grounded;

[0047] The second end of the capacitor C23 and the second end of the capacitor C15 are simultaneously connected to the pin 13 of the AD conversion chip U13;

[0048] Pin 14 of the AD conversion chip U13 is simultaneously connected to the first end of the inductor L2, the first end of the capacitor 14, and the first end of the capacitor 22. The second end of the inductor L2 is connected to a +5V voltage. The second end of the capacitor 14 and the second end of the capacitor 22 are simultaneously grounded.

[0049] The valve feedback circuit 4 includes an instrument amplifier U11, wherein a pin 1 of the instrument amplifier U11 is connected to a first end of a resistor R10, and a second end of the resistor R10 is connected to a pin 8 of the instrument amplifier U11;

[0050] Pin 2 of the instrument amplifier U11 is simultaneously connected to the first end of the capacitor C14, the first end of the capacitor C11, and the first end of the resistor R12, the second end of the capacitor C14 is grounded, and the second end of the resistor R12 is connected to the first end of the potentiometer W1;

[0051] The second end of the capacitor C11 is simultaneously connected to the pin 3 of the instrument amplifier U11, the first end of the capacitor C12, and the first end of the resistor R11, the second end of the capacitor C12 is grounded, and the second end of the resistor R11 is connected to the second end of the potentiometer W1;

[0052] The third end of the potentiometer W1 is a signal source current receiving end, and the third end of the potentiometer W1 is simultaneously connected to the first end of the resistor R14, the anode of the diode D3, and the first end of the resistor R12;

[0053] The second end of the resistor R14 is grounded, and the second end of the resistor R14 is connected to the first end of the resistor R13;

[0054] The fourth end of the potentiometer W1 is simultaneously connected to the second end of the resistor R13, the cathode of the diode D3, the second end of the resistor R12, and the first end of the inductor L2;

[0055] The second end of the inductor L2 is connected to the cathode of the diode D1, and the cathode of the diode D1 is the signal source current receiving end;

[0056] Pin 4 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C13, and a second end of the capacitor C13 is grounded;

[0057] Pin 5 of the instrument amplifier U11 is grounded;

[0058] Pin 6 of the instrument amplifier U11 is simultaneously connected to the anode of the diode D2, the first end of the resistor R15, and the cathode of the diode D4. The cathode of the diode D2 is connected to a +5V voltage. The second end of the resistor R15 is an input / output port. The anode of the diode D4 is connected to a +5V voltage.

[0059] Pin 7 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C9, and a second end of the capacitor C9 is grounded.

[0060] Example

[0061] like Figure 1 As shown, an electric valve self-regulating controller comprises:

[0062] Power module 1, AD module 2, microcontroller 3, valve feedback circuit 4, valve actuator 5, solenoid valve drive circuit 6, key module 7, display module 8, PROFIBUS interface 9, RS232 serial port 10 and wireless communication module 11;

[0063] The power module 1 is unidirectionally connected to the microcontroller 3, and the AD module 2 is unidirectionally connected to the microcontroller 3;

[0064] The power module 1 requires a 5V DC voltage, the sensor circuit, A / D, D / A, etc. require a 5V reference voltage, the operational amplifier requires a ±12V voltage, the microcontroller also requires a 2.5V core voltage, and the solenoid valve requires a 24V voltage. Since the positioner adopts a two-wire low-power design, and the positioner inputs only a current signal, it is necessary to convert the 4-20mA current into the required voltage. In the utility model, the 24V voltage converted by the current input is provided to two DC / DC modules after passing through the filter circuit, and the voltage is converted into +5V and positive and negative 12V respectively. The +5V voltage is converted into +2.5V by LM1117 and used to power the core of the microcontroller. The positive and negative 12V are used to power the operational amplifier. Among them, the positive 12V is also used to generate a +5V reference voltage to provide to the A / D conversion circuit.

[0065] The microcontroller 3 is bidirectionally connected to the PROFIBUS interface 9, the microcontroller 3 is bidirectionally connected to the RS232 serial port 10, and the microcontroller 3 is bidirectionally connected to the wireless communication module 11;

[0066] The microcontroller 3 is unidirectionally connected to the solenoid valve driving circuit 6, the microcontroller 3 is unidirectionally connected to the key module 7, and the microcontroller 3 is unidirectionally connected to the display module 8;

[0067] The solenoid valve driving circuit 6 is unidirectionally connected to the valve actuator 5 , the valve actuator 5 is unidirectionally connected to the valve feedback circuit 4 , and the valve feedback circuit 4 is unidirectionally connected to the AD module 2 .

[0068] Microcontroller 3 uses the XC164CM single-chip microcomputer, which has the characteristics of fast operation speed, good stability and strong electromagnetic compatibility. It is suitable for applications with high real-time and reliability requirements and complex electromagnetic environments. The C166 V2 core adopts a 5-level instruction pipeline mechanism (plus a 2-level pre-fetch instruction pipeline). This mechanism allows the XC164CM to execute most instructions in an average of only one CPU clock cycle, greatly improving the instruction execution speed of the microcontroller. The high-performance 16-bit CPU in the C166 V2 core integrates a multiplication and accumulation unit (MAC). The MAC unit has an independent instruction set, which enables the XC164CM to have some functions of a 16-bit fixed-point DSP and can complete more complex digital algorithms in a shorter time. For example, the MAC supports single clock cycle to complete multiplication and addition operations (16 bits x 16 bits + 32 bits) and can automatically prevent overflow of the calculation results in a saturated manner. XC164CM has expanded a rich on-chip peripheral subsystem based on the C166 V2 core, which can well meet the needs of various I / O interfaces in transmission applications.

[0069] like Figure 2 As shown, the AD module includes an AD conversion chip U13, pins 1, 2, 3, and 4 of the AD conversion chip U13 are input / output ports, pins 5 and 6 of the AD conversion chip U13 are left unconnected, and pin 7 of the AD conversion chip U13 is grounded;

[0070] Pin 8 of the AD conversion chip U13 is a current detection port, and pin 8 is connected to a first end of a resistor R21, and a second end of the resistor R21 is connected to a +5V voltage;

[0071] Pin 9 of the AD conversion chip U13 is a signal receiving port, pin 10 of the AD conversion chip U13 is a signal sending port, and pin 11 of the AD conversion chip U13 is a clock signal port;

[0072] The pin 12 of the AD conversion chip U13 is connected to the first end of the capacitor C23 and the first end of the capacitor C15 at the same time, and the pin 12 of the AD conversion chip U13 is grounded;

[0073] The second end of the capacitor C23 and the second end of the capacitor C15 are simultaneously connected to the pin 13 of the AD conversion chip U13;

[0074] Pin 14 of the AD conversion chip U13 is simultaneously connected to the first end of the inductor L2, the first end of the capacitor 14, and the first end of the capacitor 22. The second end of the inductor L2 is connected to a +5V voltage. The second end of the capacitor 14 and the second end of the capacitor 22 are simultaneously grounded.

[0075] The AD conversion chip uses an ADC chip MCP3204, which communicates with XC164CM via the SSC serial port. MCP3204 has a total of 4 analog conversion channels, which are used to convert analog quantities such as valve position feedback value, voltage setting value, current setting value, etc.

[0076] like Figure 3 As shown, the valve feedback circuit 4 includes an instrument amplifier U11, a pin 1 of the instrument amplifier U11 is connected to a first end of a resistor R10, and a second end of the resistor R10 is connected to a pin 8 of the instrument amplifier U11;

[0077] Pin 2 of the instrument amplifier U11 is simultaneously connected to the first end of the capacitor C14, the first end of the capacitor C11, and the first end of the resistor R12, the second end of the capacitor C14 is grounded, and the second end of the resistor R12 is connected to the first end of the potentiometer W1;

[0078] The second end of the capacitor C11 is simultaneously connected to the pin 3 of the instrument amplifier U11, the first end of the capacitor C12, and the first end of the resistor R11, the second end of the capacitor C12 is grounded, and the second end of the resistor R11 is connected to the second end of the potentiometer W1;

[0079] The third end of the potentiometer W1 is a signal source current receiving end, and the third end of the potentiometer W1 is simultaneously connected to the first end of the resistor R14, the anode of the diode D3, and the first end of the resistor R12;

[0080] The second end of the resistor R14 is grounded, and the second end of the resistor R14 is connected to the first end of the resistor R13;

[0081] The fourth end of the potentiometer W1 is simultaneously connected to the second end of the resistor R13, the cathode of the diode D3, the second end of the resistor R12, and the first end of the inductor L2;

[0082] The second end of the inductor L2 is connected to the cathode of the diode D1, and the cathode of the diode D1 is the signal source current receiving end;

[0083] Pin 4 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C13, and a second end of the capacitor C13 is grounded;

[0084] Pin 5 of the instrument amplifier U11 is grounded;

[0085] Pin 6 of the instrument amplifier U11 is simultaneously connected to the anode of the diode D2, the first end of the resistor R15, and the cathode of the diode D4. The cathode of the diode D2 is connected to a +5V voltage. The second end of the resistor R15 is an input / output port. The anode of the diode D4 is connected to a +5V voltage.

[0086] Pin 7 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C9, and a second end of the capacitor C9 is grounded.

[0087] Figure 3 This is a 4-20mA current signal conditioning circuit. The 4-20mA signal flows through a 120-ohm precision sampling resistor and is converted into a voltage signal. Then it is output to the ADC chip MCP3204 through the instrument amplifier LT1920. Diode D1 can prevent current reverse connection. D3 is a TVS tube that plays an overvoltage protection role. The choke is used to suppress common-mode interference. R12, R11, C11, C12, and C14 form a low-pass filter network to filter out high-frequency interference. It can be seen that the circuit has both common-mode filtering (R12 / C11, R11 / C12) and differential-mode filtering (R12+R11, C11). The total bandwidth of the filter should be at least 100 times the bandwidth of the input signal. The components should be symmetrically mounted on a printed circuit board with a large ground plane and located very close to the input of the instrument amplifier to achieve optimal performance of the filter. The time constant of common mode filtering can be calculated as follows: TCM = R12*C10 = R11*C12. The time constant of differential mode filtering can be calculated as follows: TDIFF = (R12+R11)*C11.

[0088] An instrument amplifier is a closed-loop gain unit with differential inputs and a single-ended output relative to a reference terminal. The input impedance is symmetrical and has a large value. Unlike an operational amplifier whose closed-loop gain is determined by an external resistor connected between the inverting input and the output, an instrument amplifier uses an internal feedback resistor network that isolates the signal from the input. Its gain can be set by an external resistor, with a typical value of 1 to 10,000. The LT1920 is a low-power, high-precision instrument amplifier.

[0089] The actual valve opening feedback signal comes from the sensor interface circuit. The sensor uses a high-performance conductive plastic precision potentiometer, which is an economical product with high resolution and high reliability. The sensor inputs a 5V reference voltage and outputs a feedback voltage signal. The sensor is equivalent to a potentiometer, and the voltage is divided by a resistor, so the feedback voltage signal and the valve opening are linearly corresponding.

[0090] The utility model discloses an electric valve self-regulating controller, which adopts microprocessor technology and functional modules, has the characteristics of self-calibration, self-adaptation, self-diagnosis and maintenance-free operation, has a simple structure and reasonable design, can realize automatic opening or closing of electromagnetic valves, and is easy to use.

[0091] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements contained in the spirit and scope of the attached claims.

[0092] Regarding the limitation of the protection scope of the utility model, technical personnel in the relevant field should understand that, based on the technical solution of the utility model, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the protection scope of the utility model.

Claims

1. An electric valve self-adjusting controller, characterized in that: include: Power module, AD module, microcontroller, valve feedback circuit, valve actuator, solenoid valve drive circuit, key module, display module, PROFIBUS interface, RS232 serial port and wireless communication module; The power module is unidirectionally connected to the microcontroller, and the AD module is unidirectionally connected to the microcontroller; The microcontroller is bidirectionally connected to the PROFIBUS interface, the microcontroller is bidirectionally connected to the RS232 serial port, and the microcontroller is bidirectionally connected to the wireless communication module; The microcontroller is unidirectionally connected to the solenoid valve drive circuit, the microcontroller is unidirectionally connected to the key module, and the microcontroller is unidirectionally connected to the display module; The solenoid valve driving circuit is unidirectionally connected to the valve actuator, the valve actuator is unidirectionally connected to the valve feedback circuit, and the valve feedback circuit is unidirectionally connected to the AD module.

2. The electric valve self-adjusting controller according to claim 1, characterized in that: The AD module includes an AD conversion chip U13, wherein pins 1, 2, 3 and 4 of the AD conversion chip U13 are input / output ports, pins 5 and 6 of the AD conversion chip U13 are left unconnected, and pin 7 of the AD conversion chip U13 is grounded; Pin 8 of the AD conversion chip U13 is a current detection port, and pin 8 is connected to a first end of a resistor R21, and a second end of the resistor R21 is connected to a +5V voltage; Pin 9 of the AD conversion chip U13 is a signal receiving port, pin 10 of the AD conversion chip U13 is a signal sending port, and pin 11 of the AD conversion chip U13 is a clock signal port; The pin 12 of the AD conversion chip U13 is connected to the first end of the capacitor C23 and the first end of the capacitor C15 at the same time, and the pin 12 of the AD conversion chip U13 is grounded; The second end of the capacitor C23 and the second end of the capacitor C15 are simultaneously connected to the pin 13 of the AD conversion chip U13; Pin 14 of the AD conversion chip U13 is simultaneously connected to the first end of the inductor L2, the first end of the capacitor 14, and the first end of the capacitor 22. The second end of the inductor L2 is connected to a +5V voltage. The second end of the capacitor 14 and the second end of the capacitor 22 are simultaneously grounded.

3. The electric valve self-adjusting controller according to claim 1, characterized in that: The valve feedback circuit 4 includes an instrument amplifier U11, wherein a pin 1 of the instrument amplifier U11 is connected to a first end of a resistor R10, and a second end of the resistor R10 is connected to a pin 8 of the instrument amplifier U11; Pin 2 of the instrument amplifier U11 is simultaneously connected to the first end of the capacitor C14, the first end of the capacitor C11, and the first end of the resistor R12, the second end of the capacitor C14 is grounded, and the second end of the resistor R12 is connected to the first end of the potentiometer W1; The second end of the capacitor C11 is simultaneously connected to the pin 3 of the instrument amplifier U11, the first end of the capacitor C12, and the first end of the resistor R11, the second end of the capacitor C12 is grounded, and the second end of the resistor R11 is connected to the second end of the potentiometer W1; The third end of the potentiometer W1 is a signal source current receiving end, and the third end of the potentiometer W1 is simultaneously connected to the first end of the resistor R14, the anode of the diode D3, and the first end of the resistor R12; The second end of the resistor R14 is grounded, and the second end of the resistor R14 is connected to the first end of the resistor R13; The fourth end of the potentiometer W1 is simultaneously connected to the second end of the resistor R13, the cathode of the diode D3, the second end of the resistor R12, and the first end of the inductor L2; The second end of the inductor L2 is connected to the cathode of the diode D1, and the cathode of the diode D1 is the signal source current receiving end; Pin 4 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C13, and a second end of the capacitor C13 is grounded; Pin 5 of the instrument amplifier U11 is grounded; Pin 6 of the instrument amplifier U11 is simultaneously connected to the anode of the diode D2, the first end of the resistor R15, and the cathode of the diode D4. The cathode of the diode D2 is connected to a +5V voltage. The second end of the resistor R15 is an input / output port. The anode of the diode D4 is connected to a +5V voltage. Pin 7 of the instrument amplifier U11 is connected to a -12V voltage, pin 4 of the instrument amplifier U11 is connected to a first end of a capacitor C9, and a second end of the capacitor C9 is grounded.

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