Self-detection signal acquisition circuit based on analog quantity current and voltage mixed input

Abstract

The invention provides a self-detection signal acquisition circuit based on analog quantity current and voltage mixed input, which comprises a surge protection circuit, a switch selection circuit, a clamping protection circuit, a follower circuit, an impedance matching circuit and an ADC acquisition chip which are connected in sequence, and also comprises a microcontroller, the microcontroller is connected with the ADC acquisition chip and the switch selection circuit, and the ADC acquisition chip is connected with the switch selection circuit. The microcontroller is used for acquiring the output voltage of the impedance matching circuit through the ADC acquisition chip, performing periodic detection on the output voltage of the impedance matching circuit, and periodically outputting a high level or a low level to the switch selection circuit based on the periodic detection result of the output voltage of the impedance matching circuit. Therefore, the switch selection circuit is controlled to switch gears. The technical problems that in the prior art, due to the fact that only a plurality of analog quantity signal input collecting modules of different types can be used for collecting a plurality of sensors with different output signals, the workload of sensor wiring work is large, the work efficiency is low, and the error rate is high are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of signal acquisition, and in particular to a self-detection signal acquisition circuit based on analog current and voltage mixed input. Background Art

[0002] In the industrial production process, various sensors are used, such as pressure sensors and temperature and humidity sensors. Different sensors give different signals, some give voltage signals, and some give current signals. Therefore, the analog signal input acquisition modules on the market are roughly divided into two types: voltage input type and current input type. However, for cabinet applications with many interfaces and mixed signal types, using multiple different types of analog signal input acquisition modules to collect sensor information with multiple different output signal types is extremely cumbersome in operation. In many cases, checking the error of a line requires sorting out the entire cabinet, which is a large workload, low work efficiency, and a high error rate. The wrong connection of the signal type and analog input acquisition module will cause the corresponding circuit to burn out.

[0003] Therefore, it is urgent to design a signal acquisition circuit that is compatible with voltage signal and current signal input. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a self-detection signal acquisition circuit based on analog current and voltage mixed input, which is used to solve the technical problem in the prior art that only multiple different types of analog signal input acquisition modules can be used to collect sensors with multiple different output signals, resulting in a large workload, low work efficiency and high error rate in sensor wiring work.

[0005] To achieve the above objectives, the present application embodiment adopts the following technical solutions:

[0006] A self-detection signal acquisition circuit based on analog current and voltage mixed input, used to acquire sensor signals, including a surge protection circuit, a switch selection circuit, a clamping protection circuit, a follower circuit, an impedance matching circuit, an ADC acquisition chip and a microcontroller;

[0007] The input end of the surge protection circuit is connected to the output end of the sensor;

[0008] The input end of the switch selection circuit is connected to the output end of the surge protection circuit;

[0009] The input end of the clamp protection circuit is connected to the output end of the switch selection circuit;

[0010] The input end of the follower circuit is connected to the output end of the clamp protection circuit;

[0011] The input end of the impedance matching circuit is connected to the output end of the follower circuit, and the output end thereof is connected to the ADC acquisition chip;

[0012] The input end of the microcontroller is connected to the ADC acquisition chip, and the output end thereof is connected to the enable end of the switch selection circuit. The microcontroller obtains the output voltage of the impedance matching circuit through the ADC acquisition chip, and periodically detects the output voltage of the impedance matching circuit. Based on the periodic detection result of the output voltage, the microcontroller periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears.

[0013] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the surge protection circuit includes a first bidirectional TVS diode, a second bidirectional TVS diode and a third bidirectional TVS diode;

[0014] One end of the second bidirectional TVS diode is connected to the positive output end of the sensor, and the other end is connected to the negative output end of the sensor;

[0015] One end of the first bidirectional TVS diode is connected to the forward output end of the sensor, and the other end is grounded;

[0016] One end of the third bidirectional TVS diode is connected to the negative output end of the sensor, and the other end is grounded;

[0017] The second bidirectional TVS diode is connected to the switch selection circuit.

[0018] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the surge protection circuit further includes a residual voltage discharge circuit, and the residual voltage discharge circuit includes a first high-voltage capacitor, a second high-voltage capacitor, and a third high-voltage capacitor;

[0019] One end of the first high-voltage capacitor is connected to the positive output end of the sensor, and the other end is grounded;

[0020] The second high-voltage capacitor is connected in parallel with the second forward TVS diode;

[0021] One end of the third high-voltage capacitor is connected to the negative output end of the sensor, and the other end is grounded.

[0022] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the switch selection circuit includes a switch relay, a sampling resistor, a pull-up resistor, a first voltage-dividing resistor, and a second voltage-dividing resistor;

[0023] The first normally open end of the switch relay is connected to the second end of the sampling resistor, the first end of the sampling resistor is connected to the surge protection circuit and the second normally closed end of the switch relay, the first normally closed end of the switch relay is connected to the surge protection circuit, the second normally open end of the switch relay is connected to the clamp protection circuit, the second common end of the switch relay is connected to the first voltage-dividing resistor, the other end of the first voltage-dividing resistor is connected to the clamp protection circuit and the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is grounded, one end of the pull-up resistor is connected to the negative pole of the coil of the switch relay, and the other end is connected to the control voltage, the negative pole of the coil of the switch relay serves as the enable end of the switch selection circuit, and the positive pole of the coil of the switch relay is connected to the control voltage.

[0024] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the switch selection circuit also includes a protection circuit, and the protection circuit includes a diode, a first resistor and a first capacitor;

[0025] The positive electrode of the diode is connected to the negative electrode of the coil of the switch relay, the negative electrode of the diode is connected to the positive electrode of the coil of the switch relay, the first resistor is connected in series with the first capacitor, the other end of the first resistor is connected to the positive electrode of the coil of the switch relay, and the other end of the first capacitor is connected to the negative electrode of the coil of the switch relay. The protection circuit is used to suppress the reverse peak voltage to prevent the switch relay from being damaged.

[0026] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the switch relay is a double-pole double-throw switch relay of model HFD4 / 5-SR.

[0027] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the clamping protection circuit includes a first filter capacitor, a first clamping diode and a second clamping diode;

[0028] The first end of the first filter capacitor is connected to the switch selection circuit, and the second end is grounded. The anode of the first clamping diode is connected to the first end of the first filter capacitor, and the cathode of the first clamping diode is connected to the positive power rail. The cathode of the second clamping diode is connected to the first end of the first filter capacitor, and the cathode of the second clamping diode is connected to the negative power rail.

[0029] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the follower circuit includes an operational amplifier, a second filter capacitor and a third filter capacitor;

[0030] The positive input terminal of the operational amplifier is connected to the clamp protection circuit, the output terminal of the operational amplifier is connected to the negative input terminal of the operational amplifier and the impedance matching circuit, the positive power supply terminal of the operational amplifier is connected to the positive power supply rail and the second filter capacitor, the other end of the second filter capacitor is grounded, the negative power supply terminal of the operational amplifier is connected to the negative power supply rail and the third filter capacitor, and the other end of the third filter capacitor is grounded.

[0031] In the self-detection signal acquisition circuit based on analog current and voltage mixed input described in the embodiment of the present application, the impedance matching circuit includes a first series resistor, a second series resistor, a differential mode resistor and a fourth filter capacitor;

[0032] The first series resistor, the differential mode resistor and the second series resistor are connected in series, the fourth filter capacitor is connected in parallel with the differential mode resistor, the voltage across the differential mode resistor is used as the final output voltage, and the two ends of the differential mode resistor are connected to the ADC acquisition chip and the microcontroller.

[0033] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0034] The self-detection signal acquisition circuit based on analog current and voltage mixed input provided by the embodiment of the present application suppresses and absorbs surge voltage to protect the subsequent circuit by setting a surge protection circuit, sets a switch selection circuit for switching gears, so that the signal acquisition circuit switches between receiving voltage signals or current signals, sets a clamp protection circuit to clamp the input voltage within a safe range to protect the subsequent circuit, sets a follower circuit for stably transmitting the input signal to the subsequent circuit, improves the differential mode matching of the input signal through an impedance matching circuit, and allows the input signal to smoothly enter the ADC acquisition chip. The ADC acquisition chip will output the signal to the microcontroller after analog-to-digital conversion to complete the acquisition of the sensor signal. At the same time, the microcontroller periodically detects the output voltage of the impedance matching resistor, and based on the periodic detection result of the output voltage, periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears, thereby solving the technical problem in the prior art that only multiple different types of analog signal input acquisition modules can be used to collect sensors with multiple different output signals, resulting in a large workload, low work efficiency and high error rate for sensor wiring. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. The drawings are not intended to be drawn to scale, and for the sake of clarity, not every component will be marked in each figure. The drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. Among them:

[0036] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application. DETAILED DESCRIPTION

[0037] Since the output signals of the sensor are divided into voltage signals and current signals, and the current analog signal input acquisition module can only receive voltage signals or current signals alone, in the wiring process of a cabinet with many interfaces and mixed signal types, multiple different types of analog signal input acquisition modules are used to collect sensor information of multiple different output signal types. The operation is extremely cumbersome. In many cases, it is necessary to sort out the entire cabinet to check the error of one line, which is a large workload, low work efficiency, and a high error rate. Incorrect connection of signal type and analog input acquisition module will cause the corresponding circuit to burn out.

[0038] In view of this, the embodiment of the present application provides a self-detection signal acquisition circuit based on analog current and voltage mixed input, the concept of which is to suppress and absorb surge voltage to protect the subsequent circuit by setting a surge protection circuit, set a switch selection circuit for switching gears, so that the signal acquisition circuit switches between receiving voltage signals or current signals, set a clamping protection circuit to clamp the input voltage within a safe range to protect the subsequent circuit, set a follower circuit for stably transmitting the input signal to the subsequent circuit, and improve the differential mode matching of the input signal through an impedance matching circuit, so that the input signal smoothly enters the ADC acquisition chip, and the ADC acquisition chip will output the signal to the microcontroller after analog-to-digital conversion to complete the acquisition of the sensor signal. At the same time, the microcontroller periodically detects the output voltage of the impedance matching resistor, and based on the periodic detection result of the output voltage, periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears, which solves the technical problem in the prior art that only multiple different types of analog signal input acquisition modules can be used to collect sensors with multiple different output signals, resulting in a large workload, low work efficiency and high error rate for sensor wiring.

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0041] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0043] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0044] The present application embodiment provides a self-detection signal acquisition circuit based on analog current and voltage mixed input, such as Figure 1 The self-detection signal acquisition circuit based on analog current and voltage mixed input is used to acquire the voltage signal or current signal output by the sensor, including a surge protection circuit, a switch selection circuit, a clamping protection circuit, a follower circuit, an impedance matching circuit, an ADC acquisition chip and a microcontroller.

[0045] The input end of the surge protection circuit is connected to the output end of the sensor.

[0046] Specifically, the surge protection circuit includes a first bidirectional TVS diode TV1, a second bidirectional TVS diode TV2 and a third bidirectional TVS diode TV3, one end of the second bidirectional TVS diode TV2 is connected to the positive output terminal AIN+ of the sensor, and the other end is connected to the negative output terminal AIN- of the sensor, one end of the first bidirectional TVS diode TV1 is connected to the positive output terminal AIN+ of the sensor, and the other end is grounded, one end of the third bidirectional TVS diode TV3 is connected to the negative output terminal AIN- of the sensor, and the other end is grounded, and the second bidirectional TVS diode TV2 is connected to the switch selection circuit.

[0047] Preferably, the surge protection circuit also includes a residual voltage discharge circuit, which is used to discharge the residual voltage, including a first high-voltage capacitor C2, a second high-voltage capacitor C3 and a third high-voltage capacitor C5, one end of the first high-voltage capacitor C2 is connected to the positive output terminal AIN+ of the sensor, and the other end is grounded, the second high-voltage capacitor C3 is connected in parallel with the second forward TVS diode TV2, and one end of the third high-voltage capacitor C5 is connected to the negative output terminal AIN- of the sensor, and the other end is grounded.

[0048] Among them, the models of the first bidirectional TVS diode TV1, the second bidirectional TVS diode TV2 and the third bidirectional TVS diode TV3 are all SMBJ30CA, the first high-voltage capacitor C2, the second high-voltage capacitor C3 and the third high-voltage capacitor C5 are all 4.7nF, and the surge protection circuit is used to suppress, absorb and discharge surge voltage to protect the subsequent circuit.

[0049] The input end of the switch selection circuit is connected to the output end of the surge protection circuit.

[0050] Specifically, the switch selection circuit includes a switch relay K1, a sampling resistor R1, a pull-up resistor R3, a first voltage-dividing resistor R7, and a second voltage-dividing resistor R8.

[0051] The first normally open end of the switch relay K1 is connected to the second end of the sampling resistor R1, the first end of the sampling resistor R1 is connected to the surge protection circuit and the second normally closed end of the switch relay K1, the first normally closed end of the switch relay K1 is connected to the surge protection circuit, the second normally open end of the switch relay K1 is connected to the clamping protection circuit, the second common end of the switch relay K1 is connected to the first voltage-dividing resistor R7, the other end of the first voltage-dividing resistor R7 is connected to the clamping protection circuit and the second voltage-dividing resistor R8, the other end of the second voltage-dividing resistor R8 is grounded, one end of the pull-up resistor R3 is connected to the negative pole of the coil of the switch relay K1, and the other end is connected to the control voltage, the negative pole of the coil of the switch relay K1 serves as the enabling end of the switch selection circuit, and the positive pole of the coil of the switch relay K1 is connected to the control voltage.

[0052] Preferably, the switch selection circuit also includes a protection circuit, which includes a diode D3, a first resistor R6 and a first capacitor C8, the positive electrode of the diode D3 is connected to the negative electrode of the coil of the switch relay K1, the negative electrode of the diode D3 is connected to the positive electrode of the coil of the switch relay K1, the first resistor R6 is connected in series with the first capacitor C8, the other end of the first resistor R6 is connected to the positive electrode of the coil of the switch relay K1, and the other end of the first capacitor C8 is connected to the negative electrode of the coil of the switch relay K1, and the protection circuit is used to suppress the reverse peak voltage to prevent the switch relay K1 from being damaged.

[0053] Among them, the switch relay K1 is a double-pole double-throw switch relay, and its model is HFD4 / 5-SR. The first end of the sampling resistor R1 is connected to the positive output end AIN+ of the sensor, and the first normally closed end of the switch relay K1 is connected to the negative output end AIN- of the sensor. The negative pole of the coil of the switch relay K1 serves as the enable end EN of the switch relay K1, that is, the enable end of the switch selection circuit. In this embodiment, the sampling resistor R1 is 250R, the pull-up resistor R3 is 4.7K, the first voltage divider resistor R7 and the second voltage divider resistor R8 are 100K and 500K respectively, the first resistor R6 is 1K, the first capacitor C8 is 100pF, the diode D3 is 1N4148W, and the control voltage is 5V. The switch selection circuit is used to receive the high and low level control signals of the microcontroller to switch the gear, so that the signal acquisition circuit of the embodiment of the present application switches between receiving voltage signals or current signals.

[0054] The input end of the clamp protection circuit is connected to the output end of the switch selection circuit.

[0055] Specifically, the clamping protection circuit includes a first filter capacitor C4, a first clamping diode D1 and a second clamping diode D2, the first end of the first filter capacitor C4 is connected to the switch selection circuit, and the second end is grounded, the anode of the first clamping diode D1 is connected to the first end of the first filter capacitor C4, and the cathode thereof is connected to the positive power rail, the cathode of the second clamping diode D2 is connected to the first end of the first filter capacitor C4, and the cathode thereof is connected to the negative power rail.

[0056] Among them, the clamping protection circuit is used to clamp the input voltage of the clamping protection circuit within a safe range to protect the subsequent circuit. The first end of the first filter capacitor C4 is connected to the other end of the first voltage divider resistor R7. The first filter capacitor C4 is 100nF. The first clamping diode D1 and the second clamping diode D2 are both models FHLL4148-XE. The positive power rail is +15V, and the negative power rail is -15V.

[0057] The input end of the follower circuit is connected to the output end of the clamp protection circuit.

[0058] Specifically, the follower circuit includes an operational amplifier U1, a second filter capacitor C1 and a third filter capacitor C6, the positive input terminal of the operational amplifier U1 is connected to the clamp protection circuit, the output terminal of the operational amplifier U1 is connected to the negative input terminal of the operational amplifier U1 and the impedance matching circuit, the positive power supply terminal of the operational amplifier U1 is connected to the positive power supply rail and the second filter capacitor C1, the other end of the second filter capacitor C1 is grounded, the negative power supply terminal of the operational amplifier U1 is connected to the negative power supply rail and the third filter capacitor C6, and the other end of the third filter capacitor C6 is grounded.

[0059] Among them, the model of the operational amplifier U1 is OPA188AIDR, its forward input terminal is connected to the positive electrode of the first clamping diode D1, the second filter capacitor C1 and the third filter capacitor C6 are both 100nF, the positive power rail is +15V, the negative power rail is -15V, and the follower circuit is used to stably transmit the input signal of the follower circuit to the subsequent circuit.

[0060] The input end of the impedance matching circuit is connected to the output end of the follower circuit, and its output end is connected to the ADC acquisition chip. The input end of the microcontroller is connected to the ADC acquisition chip, and its output end is connected to the enable end of the switch selection circuit. The microcontroller obtains the output voltage of the impedance matching circuit through the ADC acquisition chip, and periodically detects the output voltage of the impedance matching circuit. Based on the periodic detection result of the output voltage, the microcontroller periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears.

[0061] Specifically, the impedance matching circuit includes a first series resistor R2, a second series resistor R5, a differential mode resistor R4 and a fourth filter capacitor C7. The first series resistor R2, the differential mode resistor R4 and the second series resistor R5 are connected in series. The fourth filter capacitor C7 is connected in parallel with the differential mode resistor R4. The output voltage across the differential mode resistor R4 is used as the final output voltage. The two ends of the differential mode resistor R4 are connected to the ADC acquisition chip.

[0062] Among them, the other end of the first series resistor R2 is connected to the output end of the operational amplifier U1, the other end of the second series resistor R5 is grounded, the first series resistor R2 and the second series resistor R5 are both 1K, the differential mode resistor R4 is 10M, the fourth filter capacitor C7 is 1nF, the connection point between the differential mode resistor R4 and the first series resistor R2 is AI+, the connection point between the differential mode resistor R4 and the second series resistor R5 is AI-, the ADC acquisition chip is used to collect the output voltage between AI+ and AI- and perform analog-to-digital conversion on the voltage signal, when the microcontroller obtains the voltage through the ADC acquisition chip When the output voltage across the differential mode resistor R4 is greater than a threshold value preset in the microcontroller, the microcontroller outputs a low level to the switch relay K1, so that the sampling resistor R1 is connected to the signal acquisition circuit, so that the signal acquisition circuit of the present application receives the current signal; when the output voltage across the differential mode resistor R4 obtained by the microcontroller through the ADC acquisition chip is less than the threshold value preset in the microcontroller, the microcontroller outputs a high level to the switch relay K1, so that the first voltage-dividing resistor R7 and the second voltage-dividing resistor R8 are connected to the signal acquisition circuit, so that the signal acquisition circuit of the present application receives the voltage signal.

[0063] In summary, the self-detection signal acquisition circuit based on analog current and voltage mixed input provided by the embodiment of the present application suppresses and absorbs surge voltage to protect the subsequent circuit by setting a surge protection circuit, and sets a switch selection circuit for switching gears so that the signal acquisition circuit switches between receiving voltage signals or current signals. The clamping protection circuit is set to clamp the input voltage within a safe range to protect the subsequent circuit, and the follower circuit is set to stably transmit the input signal to the subsequent circuit. The differential mode matching of the input signal is improved by the impedance matching circuit, so that the input signal smoothly enters the ADC acquisition chip. The ADC acquisition chip will output the signal to the microcontroller after analog-to-digital conversion to complete the acquisition of the sensor signal. At the same time, the microcontroller periodically detects the output voltage of the impedance matching resistor, and based on the periodic detection result of the output voltage, periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears, which solves the technical problems in the prior art that only multiple different types of analog signal input acquisition modules can be used to collect sensors with multiple different output signals, resulting in a large workload, low work efficiency and high error rate for sensor wiring.

[0064] The above is a detailed introduction to the self-detection signal acquisition circuit based on analog current and voltage mixed input provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A self-detection signal acquisition circuit based on analog current and voltage mixed input, used to collect sensor signals, characterized in that: Including surge protection circuit, switch selection circuit, clamp protection circuit, follower circuit, impedance matching circuit, ADC acquisition chip and microcontroller; The input end of the surge protection circuit is connected to the output end of the sensor; The input end of the switch selection circuit is connected to the output end of the surge protection circuit; The input end of the clamp protection circuit is connected to the output end of the switch selection circuit; The input end of the follower circuit is connected to the output end of the clamp protection circuit; The input end of the impedance matching circuit is connected to the output end of the follower circuit, and the output end thereof is connected to the ADC acquisition chip; The input end of the microcontroller is connected to the ADC acquisition chip, and the output end thereof is connected to the enable end of the switch selection circuit. The microcontroller obtains the output voltage of the impedance matching circuit through the ADC acquisition chip, and periodically detects the output voltage of the impedance matching circuit. Based on the periodic detection result of the output voltage, the microcontroller periodically outputs a high level or a low level to the enable end of the switch selection circuit to control the switch selection circuit to switch gears.

2. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 1, characterized in that: The surge protection circuit includes a first bidirectional TVS diode, a second bidirectional TVS diode and a third bidirectional TVS diode; One end of the second bidirectional TVS diode is connected to the positive output end of the sensor, and the other end is connected to the negative output end of the sensor; One end of the first bidirectional TVS diode is connected to the forward output end of the sensor, and the other end is grounded; One end of the third bidirectional TVS diode is connected to the negative output end of the sensor, and the other end is grounded; The second bidirectional TVS diode is connected to the switch selection circuit.

3. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 2, characterized in that: The surge protection circuit further includes a residual voltage discharge circuit, and the residual voltage discharge circuit includes a first high-voltage capacitor, a second high-voltage capacitor and a third high-voltage capacitor; One end of the first high-voltage capacitor is connected to the positive output end of the sensor, and the other end is grounded; The second high-voltage capacitor is connected in parallel with the second forward TVS diode; One end of the third high-voltage capacitor is connected to the negative output end of the sensor, and the other end is grounded.

4. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 1, characterized in that: The switch selection circuit includes a switch relay, a sampling resistor, a pull-up resistor, a first voltage-dividing resistor and a second voltage-dividing resistor; The first normally open end of the switch relay is connected to the second end of the sampling resistor, the first end of the sampling resistor is connected to the surge protection circuit and the second normally closed end of the switch relay, the first normally closed end of the switch relay is connected to the surge protection circuit, the second normally open end of the switch relay is connected to the clamp protection circuit, the second common end of the switch relay is connected to the first voltage-dividing resistor, the other end of the first voltage-dividing resistor is connected to the clamp protection circuit and the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is grounded, one end of the pull-up resistor is connected to the negative pole of the coil of the switch relay, and the other end is connected to the control voltage, the negative pole of the coil of the switch relay serves as the enable end of the switch selection circuit, and the positive pole of the coil of the switch relay is connected to the control voltage.

5. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 4, characterized in that: The switch selection circuit further includes a protection circuit, wherein the protection circuit includes a diode, a first resistor and a first capacitor; The positive electrode of the diode is connected to the negative electrode of the coil of the switch relay, the negative electrode of the diode is connected to the positive electrode of the coil of the switch relay, the first resistor is connected in series with the first capacitor, the other end of the first resistor is connected to the positive electrode of the coil of the switch relay, and the other end of the first capacitor is connected to the negative electrode of the coil of the switch relay. The protection circuit is used to suppress the reverse peak voltage to prevent the switch relay from being damaged.

6. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 4, characterized in that: The switch relay is a double-pole double-throw switch relay of model HFD4 / 5-SR.

7. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 1, characterized in that: The clamp protection circuit includes a first filter capacitor, a first clamp diode and a second clamp diode; The first end of the first filter capacitor is connected to the switch selection circuit, and the second end is grounded. The anode of the first clamping diode is connected to the first end of the first filter capacitor, and the cathode of the first clamping diode is connected to the positive power rail. The cathode of the second clamping diode is connected to the first end of the first filter capacitor, and the cathode of the second clamping diode is connected to the negative power rail.

8. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 1, characterized in that: The follower circuit includes an operational amplifier, a second filter capacitor and a third filter capacitor; The positive input terminal of the operational amplifier is connected to the clamp protection circuit, the output terminal of the operational amplifier is connected to the negative input terminal of the operational amplifier and the impedance matching circuit, the positive power supply terminal of the operational amplifier is connected to the positive power supply rail and the second filter capacitor, the other end of the second filter capacitor is grounded, the negative power supply terminal of the operational amplifier is connected to the negative power supply rail and the third filter capacitor, and the other end of the third filter capacitor is grounded.

9. The self-detection signal acquisition circuit based on analog current and voltage mixed input according to claim 1, characterized in that: The impedance matching circuit includes a first series resistor, a second series resistor, a differential mode resistor and a fourth filter capacitor; The first series resistor, the differential mode resistor and the second series resistor are connected in series, the fourth filter capacitor is connected in parallel with the differential mode resistor, the voltage across the differential mode resistor is used as the final output voltage, and the two ends of the differential mode resistor are connected to the ADC acquisition chip and the microcontroller.

Images