An intelligent thermocouple control circuit

Abstract

The present invention discloses an intelligent thermocouple control circuit, which relates to the technical field of temperature detection and control, and includes a signal acquisition circuit, a signal processing circuit, a main control circuit, an isolation control circuit, and a communication circuit; the signal acquisition circuit is used to acquire the electromotive force signal output by the thermocouple and filter out the high-frequency noise of the WIFI signal and the mobile phone signal; the signal processing circuit is used to convert the electromotive force signal into a digital signal and perform cold end compensation on the thermocouple; the main control circuit is used to receive and store the acquired digital signal and control the operation and communication of the isolation control circuit. The intelligent thermocouple control circuit of the present invention adopts distributed thermocouples for multi-faceted acquisition, effectively filters, cold compensates and converts the acquired signals, improves the detection accuracy of the thermocouple, strengthens the acquisition of signals, and eliminates interference between circuits through isolation control, and has a wireless real-time monitoring function, and the control of the thermocouple is more intelligent.

Description

Technical Field

[0001] The invention relates to the technical field of temperature detection and control, in particular to an intelligent thermocouple control circuit. Background Art

[0002] With the development of industry and the improvement of social productivity, many large-scale high-temperature equipment are widely used in various fields. Temperature is one of the most commonly used parameters in industrial production. It affects the efficiency of industrial production and the safety of circuits all the time. Real-time acquisition and high-precision real-time monitoring of temperature are of great significance for applications in various fields. Among them, thermocouples have good applications in the field of high-temperature detection, but the constant temperature of the cold end (reference end) of the thermocouple sensor directly affects the measurement accuracy of the thermocouple. In order to better detect the temperature and not be affected by environmental factors such as air pressure, it is necessary to control the cold end temperature of the thermocouple. In addition, the additional protection circuit in the thermocouple control circuit increases the volume of the circuit. At the same time, the signal processing and wireless communication functions of the thermocouple temperature acquisition signal need to be optimized. Summary of the invention

[0003] The embodiment of the present invention provides an intelligent thermocouple control circuit to solve the problems raised in the above background technology.

[0004] According to a first aspect of an embodiment of the present invention, there is provided an intelligent thermocouple control circuit, the intelligent thermocouple control circuit comprising: a signal acquisition circuit, a signal processing circuit, a main control circuit, an isolation control circuit, and a communication circuit;

[0005] The signal acquisition circuit is used to collect the electromotive force signal output by the thermocouple in all directions and filter out the high-frequency noise of the WIFI signal and the mobile phone signal;

[0006] The signal processing circuit is used to convert the electromotive force signal collected by the signal collection circuit into a digital signal and perform cold end compensation on the thermocouple;

[0007] The main control circuit is used to receive the digital signal output by the signal processing circuit; to store the digital signal output by the signal processing circuit; to control the operation of the isolation control circuit; and to transmit the digital signal to the communication circuit;

[0008] The isolation control circuit is used to isolate the output signal of the main control circuit and perform overvoltage and short-circuit protection on the circuit;

[0009] The communication circuit is used for performing multi-point distributed communication of the digital signals collected by the main control circuit.

[0010] Compared with the prior art, the beneficial effects of the present invention are: the intelligent thermocouple control circuit of the present invention adopts distributed thermocouples for multi-faceted collection, effectively filters, cold compensates and converts the collected signals, improves the detection accuracy of the thermocouples, strengthens the collection of signals, and eliminates interference between circuits through isolation control, and has a wireless real-time monitoring function, so that the control of the thermocouples is more intelligent. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0012] Figure 1 The schematic block diagram of the intelligent thermocouple control circuit provided by the example of the present invention.

[0013] Figure 2 This is an intelligent thermocouple control circuit diagram provided for an example of the present invention.

[0014] Figure 3 A schematic block diagram of a communication circuit provided for an example of the present invention.

[0015] Figure 4 A communication circuit diagram provided for an example of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] See also Figure 1 , an embodiment of the present invention provides an intelligent thermocouple control circuit, the intelligent thermocouple control circuit comprising: a signal acquisition circuit 1, a signal processing circuit 2, a main control circuit 3, an isolation control circuit 4, a communication circuit 5, and a field display and keyboard circuit 6;

[0018] Specifically, the signal acquisition circuit 1 is used to collect the electromotive force signal output by the thermocouple TC; the first end of the signal acquisition circuit 1 is connected to the thermocouple TC;

[0019] The signal processing circuit 2 is used to convert the electromotive force signal collected by the signal collection circuit 1 into a digital signal; the first end of the signal processing circuit 2 is connected to the second end of the signal collection circuit 1;

[0020] The main control circuit 3 is used to receive the digital signal output by the signal processing circuit 2; to store the digital signal output by the signal processing circuit 2; to control the operation of the isolation control circuit 4; and to transmit the digital signal to the communication circuit 5; the first end of the main control circuit 3 is connected to the second end of the signal processing circuit 2;

[0021] The isolation control circuit 4 is used to isolate and control the main control circuit 3 and the load; the first end of the isolation control circuit 4 is connected to the second end of the main control circuit 3, and the second end of the isolation control circuit 4 is connected to the load;

[0022] The communication circuit 5 is used for performing multi-point distributed communication of the digital signal collected by the main control circuit 3; the communication circuit is connected to the third end of the main control circuit 3;

[0023] The field display and keyboard circuit 6 is used to display the digital signal output by the signal processing circuit 2 on site and control the operation of the isolation control circuit 4 ; the field display and keyboard circuit 6 is connected to the fourth end of the main control circuit 3 .

[0024] In a specific embodiment, in the above-mentioned signal acquisition circuit 1, an RFI filter can be used to process the sampled data, or two symmetrical first-order RC filter circuits can be used to eliminate the high-frequency noise picked up by the thermocouple TC when collecting temperature; the above-mentioned signal processing circuit 2 can use a thermocouple TC digital conversion chip that is specifically used to realize signal conversion and cold-end compensation functions for the thermocouple TC, or a temperature sensor and an operational amplifier can be used to form a cold-end compensation and analog-to-digital converter to realize the conversion of the analog quantity collected by the thermocouple TC into a digital quantity, which is convenient for the main control circuit 3 to receive; the above-mentioned main control circuit 3 can use a single-chip microcomputer or a CPU (central processing unit) to receive the digital signal in the circuit and control the operation of the isolation control circuit; the above-mentioned isolation control circuit 4 uses an isolator to control the switch tube to control the circuit's disconnection, wherein the switch tube can use a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, metal oxide semi-conductor field effect transistor), or a triode can also be used, and the conduction of the isolator is controlled by the main control circuit output control signal to control the conduction of the switch tube; the above-mentioned communication circuit 5 adopts a multi-node communication method, and can adopt ZIGBEE communication or CAN (Controller Area Network) bus method, and utilizes ZIGBEE communication or CAN communication nodes to perform wireless distributed collection of digital signals; the above-mentioned field display and keyboard circuit 6 is monitored by a host computer, which will not be repeated here.

[0025] Example 2: Based on Example 1, please refer to Figure 2 In a specific embodiment of the intelligent thermocouple control circuit of the present invention, the signal acquisition circuit 1 includes a thermocouple TC, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, a second capacitor C2 and a third capacitor C3;

[0026] Specifically, the first end of the thermocouple TC is connected to the first end of the first capacitor C1 and the first end of the third capacitor C3 through the first resistor R1, the second end of the thermocouple TC is connected to the first end of the second resistor R2 and the first end of the third resistor R3, the second end of the second resistor R2 is connected to the second end of the first capacitor C1 and the first end of the second capacitor C2, and the second end of the third resistor R3 is grounded, the second end of the second capacitor C2, and the second end of the third capacitor C3.

[0027] Further, the signal processing circuit 2 includes a first converter U2, a fourth capacitor C4 and a first voltage source +5V; the main control circuit 3 includes a first control chip U1;

[0028] Specifically, a first end of the first converter U2 is grounded and a second end of the fourth capacitor C4, a second end of the first converter U2 is connected to the second end of the first capacitor C1, a third end of the first converter U2 is connected to the first end of the first capacitor C1, a fourth end of the first converter U2 is connected to the first end of the fourth capacitor C4 and the first voltage source +5V, and a fifth end, a sixth end and a seventh end of the first converter U2 are connected to the IO port of the first control chip U1.

[0029] Further, the isolation control circuit 4 includes a fourth resistor R4, a fifth resistor R5, a first isolator U3, a second isolator U4, a sixth resistor R6, a seventh resistor R7 and a switch control circuit 401;

[0030] Specifically, the switch control circuit 401 is used to control the conduction of the switch tube in the circuit; to reduce the loss of the equipment and play a role in circuit protection;

[0031] The first end of the fourth resistor R4 is connected to the first end of the first isolator U3, the second end of the fourth resistor R4 and the second end of the fifth resistor R5 are connected to the IO port of the first control chip U1, the second end of the first isolator U3 is grounded and the second end of the second isolator U4, the third end of the first isolator U3 is connected to the first voltage source +5V and the third end of the second isolator U4, the fourth end of the first isolator U3 is connected to the first end of the sixth resistor R6, the first end of the second isolator U4 is connected to the first end of the fifth resistor R5, the fourth end of the second isolator U4 is connected to the first end of the seventh resistor R7, and the second end of the sixth resistor R6 and the second end of the seventh resistor R7 are connected to the switch control circuit 401.

[0032] Furthermore, the switch control circuit 401 includes an eighth resistor R8, a ninth resistor R9, a first switch tube M1 and a second switch tube M2;

[0033] Specifically, the first end of the eighth resistor R8 is connected to the second end of the sixth resistor R6 and the first end of the first switch tube M1, the second end of the eighth resistor R8 is grounded, the second end of the ninth resistor R9, the second end of the first switch tube M1 and the second end of the second switch tube M2, and the first end of the ninth resistor R9 is connected to the second end of the seventh resistor R7 and the first end of the second switch tube M2.

[0034] In a specific embodiment, the first voltage source can be obtained by using a 5V voltage regulator. The input voltage is converted into the required voltage by using a voltage regulator with a known output. The output voltage is stable and no extra peripheral components are required. The thermocouple TC can be a K-type thermocouple TC, a J-type thermocouple TC, an N-type thermocouple TC, a T-type thermocouple TC or an E-type thermocouple TC. The first conversion chip U2 is used to make the selection of the thermocouple TC more free. The first converter U2 can be a MAX31855 thermocouple TC output converter or a MAX6675 converter. Both are integrated circuits that greatly reduce the size and improve the working accuracy of the circuit. The first control chip U1 can be an STM32 series microcontroller or an AT89S52 microcontroller, and the control function can be diversified by independently compiling a software system. The first isolator U3 and the second isolator U4 can be optocouplers to achieve isolation control and avoid interference between circuits.

[0035] Example 3: Based on Example 1, please refer to Figure 3 and Figure 4 , in a specific embodiment of the intelligent thermocouple control circuit of the present invention, the communication circuit 5 includes a communication terminal node 501, a communication coordination module 502 and a wireless communication serial port module 503;

[0036] Specifically, the communication terminal node 501 is used to receive the data output by the main control circuit 3;

[0037] The communication coordination module 502 is used to connect the communication terminal node 501 with the wireless communication serial port module 503 to transmit data;

[0038] A wireless communication serial port module 503, used for connecting to a wireless communication device;

[0039] The first end of the communication terminal node 501 is connected to the communication end of the first control chip U1, the second end of the communication terminal node 501 is connected to the first end of the communication coordination module 502, and the second end of the communication coordination module 502 is connected to the wireless communication serial port module.

[0040] Further, the terminal node includes a first communication chip U5; the communication coordination module 502 includes a first gateway coordinator U6, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8 and a second voltage source +3.3V; the wireless communication serial port module 503 includes a first serial interface U7;

[0041] Specifically, the second end of the first gateway coordinator U6 is connected to the second voltage source +3.3V, the eleventh end of the first gateway coordinator U6 and the seventh capacitor C7 through the sixth capacitor C6, the first end of the first gateway coordinator U6 is connected to the third end of the first gateway coordinator U6 through the fourth capacitor C4, the fourth end of the first gateway coordinator U6 is connected to the fifth end of the first gateway coordinator U6 through the fifth capacitor C5, the sixth end of the first gateway coordinator U6 is connected to the ground end and the other end of the seventh capacitor C7 through the eighth capacitor C8, the seventh end and the eighth end of the first gateway coordinator U6 are connected to the IO port of the first communication chip U5, and the ninth end and the tenth end of the first gateway coordinator U6 are connected to the first serial interface U7.

[0042] In a specific embodiment, there are several communication terminal nodes 501, which can be added according to user needs, thereby increasing the sampling range of the thermocouple TC and intelligently performing sequence statistics on the sampled digital quantities. ZIGBEE communication is selected here; the first communication chip U5 adopts CC2530, and CC2430 can also be used, both of which are dedicated chips for ZIGBEE communication; the first gateway coordinator U6 can use MAX3232 chip or SP3232 chip to enhance the interaction ability of ZIGBEE communication and wireless communication serial port module 503 to avoid data loss; the first serial interface U7 uses a data interface USB connector to connect to the wireless communication device for data connection, which can connect RS (Recommended standard) communication and GPRS (General packet radio service) communication.

[0043] In the embodiment of the present invention, the temperature of the target is collected in real time by the thermocouple TC, the high-frequency noise picked up by the thermocouple TC when collecting the temperature is eliminated by the signal collection circuit 1, the accuracy of the temperature collection is improved, the collected temperature signal is converted into a digital signal by the signal processing circuit 2, and the cold end compensation is performed on the thermocouple TC to avoid the temperature difference phenomenon of the thermocouple TC, and the temperature and thermoelectric potential of the thermocouple TC are linearly corrected, and finally the digital signal is transmitted to the main control module, and the data is stored in the internal memory of the main control module and transmitted to the on-site display and keyboard circuit 6 performs on-site data monitoring and transmits it to the communication circuit 5 for remote monitoring. When the temperature exceeds or is lower than the internal set value of the main control circuit 3, the main control circuit 3 controls the isolation control circuit 4 to disconnect. In order to ensure the reliability of the two symmetrical first-order RC filter circuits, the first resistor R1, the first capacitor C1, the second resistor R2 and the second capacitor C2 need to be strictly matched, and the first capacitor C1 must be greater than or equal to ten times the second capacitor C2. In the isolation control circuit 4, the first switch tube M1 and the second switch tube M2 can realize overvoltage short-circuit protection of the circuit according to the software system of the main control circuit 3.

[0044] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An intelligent thermocouple control circuit, characterized in that: The intelligent thermocouple control circuit includes: a signal acquisition circuit, a signal processing circuit, a main control circuit, an isolation control circuit, and a communication circuit; The signal acquisition circuit is used to collect the electromotive force signal output by the thermocouple in all directions and filter out the high-frequency noise of the WIFI signal and the mobile phone signal; The signal processing circuit is used to convert the electromotive force signal collected by the signal collection circuit into a digital signal and perform cold end compensation on the thermocouple; The main control circuit is used to receive the digital signal output by the signal processing circuit, to store the digital signal output by the signal processing circuit, to control the operation of the isolation control circuit, and to transmit the digital signal to the communication circuit; The isolation control circuit is used to isolate the output signal of the main control circuit and perform overvoltage and short-circuit protection on the circuit; The communication circuit is used to perform multi-point distributed communication of the digital signal collected by the main control circuit; The main control circuit includes a first control chip; The isolation control circuit includes a fourth resistor, a fifth resistor, a first isolator, a second isolator, a sixth resistor, a seventh resistor and a switch control circuit; The switch control circuit is used to control the conduction of the switch tube in the circuit; it is used to reduce the loss of the equipment and play a role in circuit protection; The first end of the fourth resistor is connected to the first end of the first isolator, the second end of the fourth resistor and the second end of the fifth resistor are connected to the IO port of the first control chip, the second end of the first isolator is grounded and the second end of the second isolator, the third end of the first isolator is connected to the first voltage source and the third end of the second isolator, the fourth end of the first isolator is connected to the first end of the sixth resistor, the first end of the second isolator is connected to the first end of the fifth resistor, the fourth end of the second isolator is connected to the first end of the seventh resistor, and the second end of the sixth resistor and the second end of the seventh resistor are connected to the switch control circuit; The switch control circuit includes an eighth resistor, a ninth resistor, a first switch tube and a second switch tube; The first end of the eighth resistor is connected to the second end of the sixth resistor and the first end of the first switch tube, the second end of the eighth resistor is grounded, the second end of the ninth resistor, the second end of the first switch tube and the second end of the second switch tube, and the first end of the ninth resistor is connected to the second end of the seventh resistor and the first end of the second switch tube.

2. An intelligent thermocouple control circuit according to claim 1, characterized in that: The intelligent thermocouple control circuit also includes: a field display and keyboard circuit; The on-site display and keyboard circuit is used to display the digital signal output by the signal processing circuit on-site and control the operation of the isolation control circuit; The first end of the on-site display and keyboard circuit is connected to the fourth end of the main control circuit.

3. The intelligent thermocouple control circuit according to claim 1, characterized in that: The signal acquisition circuit includes a thermocouple, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and a third capacitor; The first end of the thermocouple is connected to the first end of the first capacitor and the first end of the third capacitor through the first resistor, the second end of the thermocouple is connected to the first end of the second resistor and the first end of the third resistor, the second end of the second resistor is connected to the second end of the first capacitor and the first end of the second capacitor, and the second end of the third resistor is grounded, the second end of the second capacitor and the second end of the third capacitor.

4. The intelligent thermocouple control circuit according to claim 3, characterized in that: The signal processing circuit includes a first converter, a fourth capacitor and a first voltage source; The first end of the first converter is connected to the ground and the second end of the fourth capacitor, the second end of the first converter is connected to the second end of the first capacitor, the third end of the first converter is connected to the first end of the first capacitor, the fourth end of the first converter is connected to the first end of the fourth capacitor and the first voltage source, and the fifth end, the sixth end and the seventh end of the first converter are connected to the IO port of the first control chip.

5. The intelligent thermocouple control circuit according to claim 1, characterized in that: The communication circuit includes a terminal node, a communication coordination module and a wireless communication serial port module; The terminal node is used to receive the digital signal output by the main control circuit; The communication coordination module is used to connect the terminal node with the wireless communication serial port module to transmit the digital signal; The wireless communication serial port module is used to connect to a wireless communication device; The first end of the terminal node is connected to the communication end of the first control chip, the second end of the terminal node is connected to the first end of the communication coordination module, and the second end of the communication coordination module is connected to the wireless communication serial port module.

6. The intelligent thermocouple control circuit according to claim 5, characterized in that: The terminal node includes a first communication chip; the communication coordination module includes a first converter, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor and a second voltage source; the wireless communication serial port module includes a first serial interface; The second end of the first converter is connected to the second voltage source, the eleventh end of the first converter and the seventh capacitor through the sixth capacitor, the first end of the first converter is connected to the third end of the first converter through the fourth capacitor, the fourth end of the first converter is connected to the fifth end of the first converter through the fifth capacitor, the sixth end of the first converter is connected to the ground and the other end of the seventh capacitor through the eighth capacitor, the seventh and eighth ends of the first converter are connected to the IO port of the first communication chip, and the ninth and tenth ends of the first converter are connected to the first serial interface.

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