CN219390971U

CN219390971U - Control circuit for simulating thermocouple signals

Info

Publication number: CN219390971U
Application number: CN202320242825.9U
Authority: CN
Inventors: 徐文俊; 邓玉书
Original assignee: Wuhan Kulmar Automotive Electronics Co ltd
Current assignee: Wuhan Kulmar Automotive Electronics Co ltd
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2023-07-21
Anticipated expiration: 2033-02-17

Abstract

The utility model relates to the technical field of electronic circuit design, and particularly discloses a control circuit for simulating thermocouple signals, which comprises an encoder circuit, a main control chip, a reference voltage output circuit, a DA (digital-analog) conversion circuit and a voltage-current conversion circuit. According to the utility model, the encoder circuit outputs a digital signal, the digital signal is converted into a digital signal which can be identified by a subsequent circuit by the main control chip, the DA conversion circuit converts the digital signal into a high-precision voltage signal by taking the output voltage of the reference voltage output circuit as a reference, the voltage-current conversion circuit converts the voltage signal into a current signal, and the current signal is injected into the high-precision resistor to obtain the electromotive force signals of the required analog thermocouple, so that the working condition test of certain components of the equipment to be tested under different temperatures is realized, the existing test mode for configuring the thermocouple detection equipment is replaced, the test time required by the working condition test is shorter, the test condition requirement is lower, and the test cost is greatly reduced.

Description

Control circuit for simulating thermocouple signals

Technical Field

The utility model relates to a control circuit for simulating thermocouple signals, and belongs to the technical field of electronic circuit design.

Background

In a laboratory under a normal temperature environment, some devices need to be tested under working conditions at different temperatures, and at the moment, thermocouple devices are required to generate corresponding thermoelectric signals at different temperatures so as to meet the testing requirements of related devices. The thermocouple equipment in the mode is a temperature measuring element commonly used in a temperature measuring instrument, wherein the thermocouple is a temperature sensing element, belongs to a primary instrument, can convert temperature signals into corresponding thermoelectromotive force signals under different temperature environments, and then converts the signals into temperature values of a measured medium through a secondary instrument.

In view of the above, in order to realize the working condition test of the related equipment, the related thermocouple detection equipment is also required to be equipped, so that the testing cost is consumed, the testing space is occupied, a certain time is also required to be spent on obtaining the thermoelectromotive force signals at different temperatures by utilizing the thermocouple detection equipment, and many laboratories do not have the temperature measuring environment and the temperature measuring condition, so that the implementation of the working condition test is limited.

Therefore, a new solution to the above-mentioned problems is needed for those skilled in the art.

Disclosure of Invention

Aiming at the technical problems, the utility model provides a control circuit for simulating thermocouple signals.

The control circuit for simulating the thermocouple signal comprises an encoder circuit, a main control chip, a reference voltage output circuit, a DA conversion circuit and a voltage-current conversion circuit; wherein,,

the signal output end of the encoder circuit is connected with the signal input end of the main control chip, the signal output end of the main control chip and the reference voltage output circuit are connected with the signal input end of the DA conversion circuit, the signal output end of the DA conversion circuit is connected with the input end of the voltage-current converter, and the output end of the voltage-current conversion circuit outputs the thermocouple electromotive force signal.

Further, the encoder circuit comprises an encoder EC, a first trigger U1A, a second trigger U1B, a resistor R1 and a resistor R2, wherein,

the signal input pin of the encoder EC is connected with an external digital control signal KEY, the first signal output pin of the encoder EC is connected with the signal input pin of the first trigger U1A, and the second signal output pin of the encoder EC is connected with the signal input pin of the second trigger U1B; one end of the resistor R1 is connected with a first signal output pin of the encoder EC, and the other end of the resistor R1 is connected with the working voltage VDD; one end of the resistor R2 is connected with a second signal output pin of the encoder EC, and the other end of the resistor R2 is connected with the working voltage VDD;

the signal output pin of the first trigger U1A and the signal output pin of the second trigger U1B are respectively connected with the first signal input pin and the second signal input pin of the main control chip.

Further, the power supply circuit further comprises a switching regulator U2, a diode D1, a light emitting diode D2, an inductor L1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a capacitor C7, wherein:

the anode of the diode D1 is connected with 24V, and the cathode is connected with +24V; the VIN pin of the switching regulator U2 is connected with the cathode of the diode D1; one end of the capacitor C3 is connected with the TR pin of the switching regulator U2, and the other end of the capacitor C is grounded; one end of the resistor R3 is connected with the CLK pin of the switching regulator U2, and the other end of the resistor R is grounded; one end of the resistor C4 is connected with a BOOT pin of the switching regulator U2, and the other end of the resistor C is connected with a PH pin of the switching regulator U2; one end of the resistor R4 is connected with 24V, and the other end of the resistor R is connected with an EN pin of the switching regulator U2; one end of the resistor R5 is connected with an EN pin of the switching regulator U2, and the other end of the resistor R is grounded; the capacitor C5 is connected with the resistor R5 in parallel; one end of the resistor R6 is connected with 24V, and the other end is connected with the anode of the light-emitting diode D2; the cathode of the light-emitting diode D2 is grounded; one end of a resistor R7 is connected with the COMP pin of the switching regulator U2, and the other end of the resistor R7 is connected with a capacitor C6; the other end of the capacitor C6 is grounded; one end of an inductor L1 is connected with a PH pin of the switching regulator U2 and one end of a resistor R13, and the other end of the inductor L1 is connected with a power supply voltage VCC end; the other end of the resistor R13 is connected in series with the capacitor C7; the other end of the capacitor C7 is grounded; the resistor R8 is connected with the resistor R10 in parallel, one end of the resistor R8 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R8 is connected with a power supply voltage VCC end; the resistor R9 is connected with the resistor R11 in parallel, one end of the resistor R9 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R9 is grounded; one end of a resistor R12 is connected with a PWRGD pin of the switching regulator U2, and the other end of the resistor R is connected with a power supply voltage VCC end;

the power supply voltage VCC end is connected with the main control chip and the reference voltage output circuit for power supply.

Further, the power supply circuit further includes a capacitor C8, a capacitor C9, a polarity capacitor C10, a polarity capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, and a capacitor C15, wherein:

one end of the capacitor C8 and one end of the capacitor C9 are respectively connected with the VIN pin of the switching regulator U2, and the other ends of the capacitor C10 are respectively grounded;

one end of the capacitor C12, one end of the capacitor C13 and one end of the capacitor C14 as well as the positive electrode of the polar capacitor C11 are connected with the power supply voltage VCC end, and the other ends are grounded;

one end of the capacitor C15 is connected with the COMP pin of the switching regulator U2, and the other end of the capacitor C is grounded.

Further, the power supply circuit further includes a zener diode D3, a light emitting diode D4, and a resistor R14, where:

the positive electrode of the voltage stabilizing diode D3 is grounded, and the negative electrode of the voltage stabilizing diode D is connected with the PH pin of the switching voltage stabilizer U2;

the anode of the light-emitting diode D4 is connected with one end of the resistor R14, and the cathode is grounded; the other end of the resistor R14 is connected to the supply voltage VCC terminal.

Further, the reference voltage output circuit includes an isolation module U3, a capacitor C16, a capacitor C17, a capacitor C18, a resistor R15, and a resistor R16, where:

the positive input end of the isolation module U3 is connected with the power supply voltage VCC end, the negative input end of the isolation module U3 is grounded, and the positive output end of the isolation module U3 is connected with the DA conversion circuit; the negative electrode output end of the isolation module U3 is connected with-5V voltage;

the capacitor C16 is connected between the positive electrode input end and the negative electrode input end of the isolation module U3; the capacitor C17 is connected in parallel with the resistor R15, one end of the capacitor C is connected with the positive electrode output end of the isolation module U3, the other end of the capacitor C is connected with the zero potential output end of the isolation module U3, and the zero potential output end of the isolation module U3 is grounded; the capacitor C18 is connected in parallel with the resistor R16, one end of the capacitor C is connected with the negative electrode output end of the isolation module U3, and the other end of the capacitor C is connected with the zero potential output end of the isolation module U3.

Further, the DA conversion circuit includes a DA conversion chip U4, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, and a capacitor C19, where:

the SCLK pin, DIN pin and DOUT pin of the DA conversion chip U4 are connected with the main control chip; DA conversion chip U4The pin is connected with the main control chip through a resistor R17; one end of each of the resistor R18, the resistor R19, the resistor R20 and the resistor R21 is connected with the positive output end of the isolation module U3, and the other end of the resistor R18 is connected with +_ of the DA conversion chip U4>The other end of the resistor R19 is connected with a MODE pin of the DA conversion chip U4, and the other end of the resistor R20 is connected with +.>The other end of the resistor R21 is connected with the FS pin of the DA conversion chip U4; the AVDD pin and the DAVCC pin of the DA conversion chip U4 are connected with the positive output end of the isolation module U3; the AAGND pin and the DAGND pin of the DA conversion chip U4 are connected with the zero-potential output end of the isolation module U3; the REF pin of the DA conversion chip U4 is connected with the zero potential output end of the isolation module U3 through a capacitor C19; the signal output end of the DA conversion chip U4 is connected with the input end of the voltage-current conversion circuit.

Further, the voltage-current conversion circuit includes a voltage-current conversion chip U5, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a capacitor C20, a capacitor C21, a capacitor C22, and a triode Q1 and a field effect transistor Q2, wherein:

one end of the resistor R22 is connected with the signal output end of the DA conversion chip U4, and the other end of the resistor R is connected with the VIN pin of the voltage-current conversion chip U5; one end of the resistor R22 is connected with a PWM pin of the main control chip, and the other end of the resistor R is connected with a VIN pin of the voltage-current conversion chip U5; one end of the capacitor C20 is connected with the VIN pin of the voltage-current conversion chip U5, and the other end of the capacitor C is grounded; the resistor R24 is connected between the REGF pin and the REGS pin of the voltage-current conversion chip U5; one end of the resistor R25 is connected with the REGS pin of the voltage-current conversion chip U5, and the other end of the resistor R is grounded; the VSP pin of the voltage-current conversion chip U5 is connected with +24V voltage, and the OD pin is connected with the zero potential output end of the isolation module U3; one end of the capacitor C21 is connected with a VSP pin of the voltage-current conversion chip U5, and the other end of the capacitor C is connected with a zero-potential output end of the isolation module U3; the base electrode of the triode Q1 IS connected with the source electrode of the field effect transistor Q2, the collector electrode of the triode Q1 IS connected with the VG pin of the voltage-current conversion chip U5 and the grid electrode of the field effect transistor Q2, and the emitter electrode of the triode Q1 IS connected with the IS pin of the voltage-current conversion chip U5; the drain electrode of the field effect tube Q2 is connected with one end of a resistor R27 and one end of a capacitor C22; the resistor R26 is connected between the emitter and the base of the triode Q1; the other end of the resistor R27 is a current output end of the voltage-current conversion circuit; the other end of the capacitor C22 is grounded.

Further, the device further comprises an analog electromotive force signal output circuit, wherein the analog electromotive force signal output circuit comprises a resistor R29, a resistor R30, a resistor R31, a capacitor C23, a capacitor C24, a capacitor C25, a fuse F1 and a fuse F2, and the like, wherein:

one end of a resistor R29 is connected with the current output end of the voltage-current conversion circuit, and the other end of the resistor R29 is connected with one end of a resistor R30, one end of a capacitor C23, one end of a capacitor C24 and one end of a fuse F1; the other end of the resistor R30 is connected with one end of the resistor R31, the other end of the capacitor C24, one end of the capacitor C25 and one end of the fuse F2; the other end of the resistor R31 is grounded; the other end of the capacitor C25 is grounded; the other end of the fuse F1 is a first analog signal output end, and the other end of the fuse F2 is a second analog signal output end.

According to the control circuit for the analog thermocouple signal, the encoder circuit outputs the digital signal, the main control chip converts the digital signal into the digital signal which can be identified by the subsequent circuit, the DA conversion circuit converts the digital signal into the high-precision voltage signal by taking the output voltage of the reference voltage output circuit as the reference, the voltage-current conversion circuit converts the voltage signal into the current signal, and the current signal is injected into the high-precision resistor to obtain the required electromotive force signal of the analog thermocouple, so that the working condition test of certain parts of the equipment to be tested under different temperatures is realized, the existing testing mode for configuring the thermocouple detection equipment is replaced, the testing time required by the working condition test is shorter, the testing condition requirement is lower, the testing cost is greatly reduced, and the popularization value is very high.

Drawings

For a clearer description of embodiments of the utility model or of solutions in the prior art, the drawings which are used in the description of the embodiments or of the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the utility model, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.

FIG. 1 is a circuit diagram of a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of an encoder circuit in a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of a power supply circuit in a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

FIG. 4 is a schematic diagram of a reference voltage output circuit in a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

FIG. 5 is a schematic diagram of a DA conversion circuit in a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a voltage-to-current conversion circuit in a control circuit for simulating thermocouple signals according to an embodiment of the present utility model;

fig. 7 is a schematic diagram of an analog electromotive force signal output circuit in a control circuit for an analog thermocouple signal according to an embodiment of the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to fall within the scope of the utility model.

As shown in fig. 1, the control circuit for simulating the thermocouple signal in the embodiment of the utility model comprises an encoder circuit 10, a main control chip 20, a reference voltage output circuit 30, a DA conversion circuit 40 and a voltage-current conversion circuit 50; the signal output end of the encoder circuit 10 is connected to the signal input end of the main control chip 20, the signal output end of the main control chip 20 and the reference voltage output circuit 40 are connected to the signal input end of the DA conversion circuit 30, the signal output end of the DA conversion circuit 30 is connected to the input end of the voltage-current converter 50, and the output end of the voltage-current converter 50 outputs the thermocouple electromotive force signal.

According to the utility model, the encoder circuit 10 outputs a digital signal, the digital signal is converted into a digital signal which can be identified by a subsequent circuit by the main control chip 20, the DA conversion circuit 40 converts the digital signal into a high-precision voltage signal by taking the output voltage of the reference voltage output circuit 30 as a reference, the voltage-current conversion circuit 50 converts the voltage signal into a current signal, and the current signal is injected into a high-precision resistor to obtain the electromotive force signal of a required analog thermocouple, so that the working condition test of certain parts of the equipment to be tested under different temperatures is realized, the existing testing mode for configuring the thermocouple detection equipment is replaced, the testing time required by the working condition test of the utility model is shorter, the testing condition requirement is lower, the testing cost is greatly reduced, and the popularization value is very high.

Specifically, as shown in fig. 2, the encoder circuit in the embodiment of the present utility model includes an encoder EC, a first trigger U1A, a second trigger U1B, a resistor R1 and a resistor R2, where a signal input pin of the encoder EC is connected to an external digital control signal KEY, a first signal output pin of the encoder EC is connected to a signal input pin of the first trigger U1A, and a second signal output pin of the encoder EC is connected to a signal input pin of the second trigger U1B; one end of the resistor R1 is connected with a first signal output pin of the encoder EC, and the other end of the resistor R1 is connected with the working voltage VDD; one end of the resistor R2 is connected with a second signal output pin of the encoder EC, and the other end of the resistor R2 is connected with the working voltage VDD; the signal output pin of the first trigger U1A and the signal output pin of the second trigger U1B are respectively connected with the first signal input pin and the second signal input pin of the main control chip.

Two signal output pins of the encoder CE are respectively connected with the first trigger U1A and the second trigger U1B, so as to respectively generate two paths of digital signals of IOC00 and IOC01, and the digital signals are connected to the signal input pins of the main control chip. The embodiment of the utility model is not limited to the specific model of the main control chip, is preferably realized by a singlechip, and has multiple paths of input and output pins, and a person skilled in the art can select relevant pin connection according to industry experience when in specific realization, and the embodiment is not limited specifically.

In the first flip-flop U1A shown in FIG. 2, the signal input pin is the 1CLK pin, the signal output pin is the 1Q pin, the 1D pin andpin connection, GND pin grounding, VCC pin connection operating voltage VDD, < >>The pin is also connected with the working voltage VDD, ">The pin is connected with a second signal output pin of the encoder EC; in the second trigger U1B, the signal input pin is a 2CLK pin, the signal output pin is a 2Q pin, a 2D pin and +.>Pin connection, a->The pins are connected with the working voltage VDD, ">The pin is connected to a first signal output pin of the encoder EC.

As shown in fig. 2, the encoder circuit further includes a capacitor C1 and a capacitor C2, wherein one end of the capacitor C1 is connected to the first signal output pin of the encoder EC, the other end of the capacitor C2 is grounded, and one end of the capacitor C2 is connected to the VCC pin of the first trigger U1A, and the other end of the capacitor C2 is grounded.

The embodiment of the utility model is not limited to specific chip types of the first trigger U1A and the second trigger U1B, and can be the same signal or different types, and only needs to achieve the connection required by the embodiment.

Specifically, the embodiment of the present utility model further includes a power supply circuit, as shown in fig. 3, where the power supply circuit includes a switching regulator U2, a diode D1, a light emitting diode D2, an inductor L1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a capacitor C7, where: the anode of the diode D1 is connected with 24V, and the cathode is connected with +24V; the VIN pin of the switching regulator U2 is connected with the cathode of the diode D1; one end of the capacitor C3 is connected with the TR pin of the switching regulator U2, and the other end of the capacitor C is grounded; one end of the resistor R3 is connected with the CLK pin of the switching regulator U2, and the other end of the resistor R is grounded; one end of the resistor C4 is connected with a BOOT pin of the switching regulator U2, and the other end of the resistor C is connected with a PH pin of the switching regulator U2; one end of the resistor R4 is connected with 24V, and the other end of the resistor R is connected with an EN pin of the switching regulator U2; one end of the resistor R5 is connected with an EN pin of the switching regulator U2, and the other end of the resistor R is grounded; the capacitor C5 is connected with the resistor R5 in parallel; one end of the resistor R6 is connected with 24V, and the other end is connected with the anode of the light-emitting diode D2; the cathode of the light-emitting diode D2 is grounded; one end of a resistor R7 is connected with the COMP pin of the switching regulator U2, and the other end of the resistor R7 is connected with a capacitor C6; the other end of the capacitor C6 is grounded; one end of an inductor L1 is connected with a PH pin of the switching regulator U2 and one end of a resistor R13, and the other end of the inductor L1 is connected with a power supply voltage VCC end; the other end of the resistor R13 is connected in series with the capacitor C7; the other end of the capacitor C7 is grounded; the resistor R8 is connected with the resistor R10 in parallel, one end of the resistor R8 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R8 is connected with a power supply voltage VCC end; the resistor R9 is connected with the resistor R11 in parallel, one end of the resistor R9 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R9 is grounded; one end of the resistor R12 is connected to the PWRGD pin of the switching regulator U2, and the other end is connected to the power supply voltage VCC terminal. The led D2 is used for indicating the normal power supply of +24v, and the VIN pin of the switching regulator U2 is connected to +24v, so that when the led D2 is in the on state, it is indicated that the high potential of the switching regulator U2 is connected normally.

In the embodiment of the utility model, the power supply voltage VCC end is connected with the main control chip and the reference voltage output circuit to supply power to the main control chip and the reference voltage output circuit. The embodiment is not limited to specific product parameters of each electrical element in the circuit design diagram in fig. 3, and in general, the supply voltage VCC can meet the supply voltage requirement of most chips by making the voltage value of the supply voltage VCC 5V. The switching regulator U2 in this embodiment may be implemented by TPS57060 series chips.

Specifically, as shown in fig. 3, the power supply circuit in the embodiment of the present utility model further includes a capacitor C8, a capacitor C9, a polarity capacitor C10, a polarity capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, and a capacitor C15, where: one end of the capacitor C8 and one end of the capacitor C9 are respectively connected with the VIN pin of the switching regulator U2, and the other ends of the capacitor C10 are respectively grounded; one end of the capacitor C12, one end of the capacitor C13 and one end of the capacitor C14 as well as the positive electrode of the polar capacitor C11 are connected with the power supply voltage VCC end, and the other ends are grounded; one end of the capacitor C15 is connected with the COMP pin of the switching regulator U2, and the other end of the capacitor C is grounded. On the basis of the above embodiment, a polar capacitor and a common capacitor are added for filtering so as to improve the voltage quality and reduce the line loss.

Specifically, as shown in fig. 3, the power supply circuit in the embodiment of the present utility model further includes a zener diode D3, a light emitting diode D4, and a resistor R14, where: the positive electrode of the voltage stabilizing diode D3 is grounded, and the negative electrode of the voltage stabilizing diode D is connected with the PH pin of the switching voltage stabilizer U2; the anode of the light-emitting diode D4 is connected with one end of the resistor R14, and the cathode is grounded; the other end of the resistor R14 is connected to the supply voltage VCC terminal. The zener diode D3 is configured to make the voltage in a stable state when the voltage in the line fluctuates, and the light emitting diode D4 has an indication function, and when the power supply voltage VCC is output normally, the light emitting diode D4 is turned on.

Specifically, as shown in fig. 4, the reference voltage output circuit in the embodiment of the present utility model includes an isolation module U3, a capacitor C16, a capacitor C17, a capacitor C18, a resistor R15, and a resistor R16, where: the positive input end of the isolation module U3 is connected with the power supply voltage VCC end, the negative input end of the isolation module U3 is grounded, and the positive output end of the isolation module U3 is connected with the DA conversion circuit; the negative electrode output end of the isolation module U3 is connected with-5V voltage; the capacitor C16 is connected between the positive electrode input end and the negative electrode input end of the isolation module U3; the capacitor C17 is connected in parallel with the resistor R15, one end of the capacitor C is connected with the positive electrode output end of the isolation module U3, the other end of the capacitor C is connected with the zero potential output end of the isolation module U3, and the zero potential output end of the isolation module U3 is grounded; the capacitor C18 is connected in parallel with the resistor R16, one end of the capacitor C is connected with the negative electrode output end of the isolation module U3, and the other end of the capacitor C is connected with the zero potential output end of the isolation module U3. The capacitor C16, the capacitor C17 and the capacitor C18 all play a role in isolation, and the positive output end of the isolation module U3 is denoted as AVCC and is input into the DA conversion circuit.

Specifically, as shown in fig. 5, the DA conversion circuit in the embodiment of the present utility model includes a DA conversion chip U4, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, and a capacitor C19, where: the SCLK pin, DIN pin and DOUT pin of the DA conversion chip U4 are connected with the main control chip; DA conversion chip U4The pin is connected with the main control chip through a resistor R17; one end of each of the resistor R18, the resistor R19, the resistor R20 and the resistor R21 is connected with the positive output end of the isolation module U3, and the other end of the resistor R18 is connected with +_ of the DA conversion chip U4>The other end of the resistor R19 is connected with a MODE pin of the DA conversion chip U4, and the other end of the resistor R20 is connected with +.>The other end of the resistor R21 is connected with the FS pin of the DA conversion chip U4; the AVDD pin and the DAVCC pin of the DA conversion chip U4 are connected with the positive output end of the isolation module U3; the AAGND pin and the DAGND pin of the DA conversion chip U4 are connected with the zero-potential output end of the isolation module U3; the REF pin of the DA conversion chip U4 is connected with the zero potential output end of the isolation module U3 through a capacitor C19; the signal output end of the DA conversion chip U4 is connected with the input end of the voltage-current conversion circuit.

As shown in fig. 5, the DA conversion chip U4The pin is connected with the main control chip through a resistor R17, and a DAC0_EN/M end in the figure is represented as a signal pin of the main control chip. The SCLK pin, DIN pin, DOUT pin and the like of the DA conversion chip U4 are connected with the corresponding function pins of the main control chip. The signal output end of the DA conversion chip U4 comprises 8 output pins of DAC_OUTA-H, and one of the output pins can be selected to meet the use requirement. The pins are provided with chips of which the product model of the DA conversion chip U4 is TVL5610 series as shown in fig. 5, and other types of chips can be used by those skilled in the art to realize conversion from digital signals to analog signals.

Specifically, as shown in fig. 6, the voltage-current conversion circuit in the embodiment of the present utility model includes a voltage-current conversion chip U5, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a capacitor C20, a capacitor C21, a capacitor C22, and a triode Q1 and a field effect transistor Q2, wherein: one end of the resistor R22 is connected with the signal output end of the DA conversion chip U4, and the other end of the resistor R is connected with the VIN pin of the voltage-current conversion chip U5; one end of the resistor R22 is connected with a PWM pin of the main control chip, and the other end of the resistor R is connected with a VIN pin of the voltage-current conversion chip U5; one end of the capacitor C20 is connected with the VIN pin of the voltage-current conversion chip U5, and the other end of the capacitor C is grounded; the resistor R24 is connected between the REGF pin and the REGS pin of the voltage-current conversion chip U5; one end of the resistor R25 is connected with the REGS pin of the voltage-current conversion chip U5, and the other end of the resistor R is grounded; the VSP pin of the voltage-current conversion chip U5 is connected with +24V voltage, and the OD pin is connected with the zero potential output end of the isolation module U3; one end of the capacitor C21 is connected with a VSP pin of the voltage-current conversion chip U5, and the other end of the capacitor C is connected with a zero-potential output end of the isolation module U3; the base electrode of the triode Q1 IS connected with the source electrode of the field effect transistor Q2, the collector electrode of the triode Q1 IS connected with the VG pin of the voltage-current conversion chip U5 and the grid electrode of the field effect transistor Q2, and the emitter electrode of the triode Q1 IS connected with the IS pin of the voltage-current conversion chip U5; the drain electrode of the field effect tube Q2 is connected with one end of a resistor R27 and one end of a capacitor C22; the resistor R26 is connected between the emitter and the base of the triode Q1; the other end of the resistor R27 is a current output end of the voltage-current conversion circuit; the other end of the capacitor C22 is grounded.

As shown in fig. 6, the current output end of the voltage-current conversion circuit is denoted as IOUT1, and the electromotive force signal of the required analog thermocouple can be obtained by injecting the current signal into the high-precision resistor.

Specifically, the embodiment of the present utility model further includes an analog electromotive force signal output circuit, as shown in fig. 7, where the analog electromotive force signal output circuit includes a resistor R29, a resistor R30, a resistor R31, a capacitor C23, a capacitor C24, a capacitor C25, a fuse F1, and a fuse F2, where: one end of a resistor R29 is connected with the current output end of the voltage-current conversion circuit, and the other end of the resistor R29 is connected with one end of a resistor R30, one end of a capacitor C23, one end of a capacitor C24 and one end of a fuse F1; the other end of the resistor R30 is connected with one end of the resistor R31, the other end of the capacitor C24, one end of the capacitor C25 and one end of the fuse F2; the other end of the resistor R31 is grounded; the other end of the capacitor C25 is grounded; the other end of the fuse F1 is a first analog signal output end, and the other end of the fuse F2 is a second analog signal output end; the voltage signals output by the first analog signal output end and the second analog signal output end are thermocouple electromotive force signals and are used for working condition test.

In the analog electromotive force signal output circuit shown in fig. 7, it is preferable that the resistor R29 and the resistor R31 are resistors with the same parameters, and the capacitor C23 and the capacitor C25 are capacitors with the same parameters. The specific product parameters of the capacitor R30 are not limited in this embodiment, and the resistance values thereof determine the voltage values of the first analog signal output terminal thermo coupler 1_p and the second analog signal output terminal thermo coupler 1_n, which can be selected by those skilled in the art according to specific test requirements.

The utility model has been further described with reference to specific embodiments, but it should be understood that the detailed description is not to be construed as limiting the spirit and scope of the utility model, but rather as providing those skilled in the art with the benefit of this disclosure with the benefit of their various modifications to the described embodiments.

Claims

1. A control circuit for simulating a thermocouple signal is characterized in that: the control circuit comprises an encoder circuit, a main control chip, a reference voltage output circuit, a DA conversion circuit and a voltage-current conversion circuit; wherein,,

the signal output end of the encoder circuit is connected with the signal input end of the main control chip, the signal output end of the main control chip and the reference voltage output circuit are connected with the signal input end of the DA conversion circuit, the signal output end of the DA conversion circuit is connected with the input end of the voltage-current converter, and the output end of the voltage-current conversion circuit outputs a thermocouple electromotive force signal.

2. The control circuit for simulating thermocouple signals according to claim 1, wherein: the encoder circuit comprises an encoder EC, a first trigger U1A, a second trigger U1B, a resistor R1 and a resistor R2, wherein,

the signal input pin of the encoder EC is connected to an external digital control signal KEY, the first signal output pin of the encoder EC is connected with the signal input pin of the first trigger U1A, and the second signal output pin of the encoder EC is connected with the signal input pin of the second trigger U1B; one end of the resistor R1 is connected with a first signal output pin of the encoder EC, and the other end of the resistor R1 is connected with a working voltage VDD; one end of the resistor R2 is connected with a second signal output pin of the encoder EC, and the other end of the resistor R2 is connected with the working voltage VDD;

3. The control circuit for simulating thermocouple signals according to claim 1, wherein: still include power supply circuit, power supply circuit includes switching regulator U2, diode D1, emitting diode D2, inductance L1, resistance R3, resistance R4, resistance R5, resistance R6, resistance R7, resistance R8, resistance R9, resistance R10, resistance R11, resistance R12, resistance R13 to and electric capacity C3, electric capacity C4, electric capacity C5, electric capacity C6, electric capacity C7, wherein:

the anode of the diode D1 is connected with 24V, and the cathode of the diode D1 is connected with +24V; the VIN pin of the switching regulator U2 is connected with the cathode of the diode D1; one end of the capacitor C3 is connected with the TR pin of the switching regulator U2, and the other end of the capacitor C is grounded; one end of the resistor R3 is connected with the CLK pin of the switching regulator U2, and the other end of the resistor R is grounded; one end of the resistor C4 is connected with a BOOT pin of the switching regulator U2, and the other end of the resistor C is connected with a PH pin of the switching regulator U2; one end of the resistor R4 is connected with 24V, and the other end of the resistor R is connected with an EN pin of the switching regulator U2; one end of the resistor R5 is connected with an EN pin of the switching regulator U2, and the other end of the resistor R is grounded; the capacitor C5 is connected with the resistor R5 in parallel; one end of the resistor R6 is connected with 24V, and the other end of the resistor R6 is connected with the positive electrode of the light-emitting diode D2; the negative electrode of the light-emitting diode D2 is grounded; one end of the resistor R7 is connected with the COMP pin of the switching regulator U2, and the other end of the resistor R7 is connected with the capacitor C6; the other end of the capacitor C6 is grounded; one end of the inductor L1 is connected with a PH pin of the switching regulator U2 and one end of the resistor R13, and the other end of the inductor L1 is connected with a power supply voltage VCC end; the other end of the resistor R13 is connected with the capacitor C7 in series; the other end of the capacitor C7 is grounded; the resistor R8 is connected with the resistor R10 in parallel, one end of the resistor R8 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R8 is connected with the power supply voltage VCC end; the resistor R9 is connected with the resistor R11 in parallel, one end of the resistor R9 is connected with a VSENSE pin of the switching regulator U2, and the other end of the resistor R9 is grounded; one end of the resistor R12 is connected with the PWRGD pin of the switching regulator U2, and the other end of the resistor R is connected with the power supply voltage VCC end;

and the power supply voltage VCC end is connected with the main control chip and the reference voltage output circuit for supplying power.

4. A control circuit for simulating a thermocouple signal according to claim 3, wherein: the power supply circuit further comprises a capacitor C8, a capacitor C9, a polarity capacitor C10, a polarity capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14 and a capacitor C15, wherein:

one end of the capacitor C8 and one end of the capacitor C9 and the positive electrode of the polarity capacitor C10 are connected with the VIN pin of the switching regulator U2, and the other ends of the capacitor C8 and the capacitor C10 are grounded;

one end of the capacitor C12, one end of the capacitor C13 and one end of the capacitor C14, and the positive electrode of the polarity capacitor C11 are connected with the power supply voltage VCC end, and the other ends of the capacitor C12 and the capacitor C14 are grounded;

5. A control circuit for simulating a thermocouple signal according to claim 3, wherein: the power supply circuit further comprises a zener diode D3, a light emitting diode D4 and a resistor R14, wherein:

the positive electrode of the voltage stabilizing diode D3 is grounded, and the negative electrode of the voltage stabilizing diode D3 is connected with the PH pin of the switching voltage stabilizer U2;

the positive electrode of the light-emitting diode D4 is connected with one end of the resistor R14, and the negative electrode is grounded; the other end of the resistor R14 is connected with the power supply voltage VCC end.

6. A control circuit for simulating a thermocouple signal according to claim 3, wherein: the reference voltage output circuit comprises an isolation module U3, a capacitor C16, a capacitor C17, a capacitor C18, a resistor R15 and a resistor R16, wherein:

the positive electrode input end of the isolation module U3 is connected with the power supply voltage VCC end, the negative electrode input end of the isolation module U3 is grounded, and the positive electrode output end of the isolation module U3 is connected with the DA conversion circuit; the negative electrode output end of the isolation module U3 is connected with-5V voltage;

7. The control circuit for simulating thermocouple signals according to claim 6, wherein: the DA conversion circuit comprises a DA conversion chip U4, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21 and a capacitor C19, wherein:

the SCLK pin, DIN pin and DOUT pin of the DA conversion chip U4 are connected with the main control chip; the DA conversion chip U4The pin is connected with the main control chip through the resistor R17; one end of each of the resistor R18, the resistor R19, the resistor R20 and the resistor R21 is connected with the positive electrode output end of the isolation module U3,the other end of the resistor R18 is connected with the DA conversion chip U4>The other end of the resistor R19 is connected with a MODE pin of the DA conversion chip U4, and the other end of the resistor R20 is connected with +.>The other end of the resistor R21 is connected with the FS pin of the DA conversion chip U4; the AVDD pin and the DAVCC pin of the DA conversion chip U4 are connected with the positive output end of the isolation module U3; the AAGND pin and the DAGND pin of the DA conversion chip U4 are connected with the zero-potential output end of the isolation module U3; the REF pin of the DA conversion chip U4 is connected with the zero potential output end of the isolation module U3 through a capacitor C19; the signal output end of the DA conversion chip U4 is connected with the input end of the voltage-current conversion circuit.

8. The control circuit for simulating thermocouple signals according to claim 7, wherein: the voltage-current conversion circuit comprises a voltage-current conversion chip U5, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a capacitor C20, a capacitor C21, a capacitor C22, a triode Q1 and a field effect transistor Q2, wherein:

one end of the resistor R22 is connected with the signal output end of the DA conversion chip U4, and the other end of the resistor R is connected with the VIN pin of the voltage-current conversion chip U5; one end of the resistor R22 is connected with the PWM pin of the main control chip, and the other end of the resistor R is connected with the VIN pin of the voltage-current conversion chip U5; one end of the capacitor C20 is connected with the VIN pin of the voltage-current conversion chip U5, and the other end of the capacitor C is grounded; the resistor R24 is connected between the REGF pin and the REGS pin of the voltage-current conversion chip U5; one end of the resistor R25 is connected with the REGS pin of the voltage-current conversion chip U5, and the other end of the resistor R is grounded; the VSP pin of the voltage-current conversion chip U5 is connected with +24V voltage, and the OD pin is connected with the zero potential output end of the isolation module U3; one end of the capacitor C21 is connected with a VSP pin of the voltage-current conversion chip U5, and the other end of the capacitor C is connected with a zero potential output end of the isolation module U3; the base electrode of the triode Q1 IS connected with the source electrode of the field effect transistor Q2, the collector electrode of the triode Q1 IS connected with the VG pin of the voltage-current conversion chip U5 and the grid electrode of the field effect transistor Q2, and the emitter electrode of the triode Q1 IS connected with the IS pin of the voltage-current conversion chip U5; the drain electrode of the field effect transistor Q2 is connected with one end of the resistor R27 and one end of the capacitor C22; the resistor R26 is connected between the emitter and the base of the triode Q1; the other end of the resistor R27 is a current output end of the voltage-current conversion circuit; the other end of the capacitor C22 is grounded.

9. The control circuit for simulating thermocouple signals according to claim 8, wherein: still include analog electromotive force signal output circuit, analog electromotive force signal output circuit includes resistance R29, resistance R30, resistance R31, electric capacity C23, electric capacity C24, electric capacity C25, fuse F1 and fuse F2, wherein:

one end of the resistor R29 is connected with the current output end of the voltage-current conversion circuit, and the other end of the resistor R29 is connected with one end of the resistor R30, one end of the capacitor C23, one end of the capacitor C24 and one end of the fuse F1; the other end of the resistor R30 is connected with one end of the resistor R31, the other end of the capacitor C24, one end of the capacitor C25 and one end of the fuse F2; the other end of the resistor R31 is grounded; the other end of the capacitor C25 is grounded; the other end of the fuse F1 is a first analog signal output end, and the other end of the fuse F2 is a second analog signal output end.