A wide range and high precision temperature conditioning circuit

Abstract

The present invention belongs to the technical field of electronic circuits, and discloses a wide-range high-precision temperature conditioning circuit, including a differential amplifier circuit and an isolation amplifier circuit; wherein the differential amplifier circuit is divided into a differential amplifier module and a subtraction module, and the temperature signal of the PT100 platinum resistance temperature sensor is filtered out by the differential amplifier module to remove common-mode interference, and then the subtraction module performs subtraction before secondary amplification to expand the acquisition range, and then sends it to the isolation amplifier circuit, and the isolation amplifier circuit is divided into a common-phase proportional amplifier module and an isolation module, and the common-phase proportional amplifier module performs secondary amplification on the transmitted signal, and then the isolation module isolates it and sends it to the test equipment. The present invention is characterized in that it is a temperature conditioning circuit designed based on a differential amplifier circuit, and has the characteristics of amplifying weak signals, filtering out clutter interference, isolating input and output, protecting test equipment, and having strong anti-interference ability, and the corresponding ambient temperature range can reach ‑60°C to 300°C.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits, and relates to a temperature conditioning circuit of a wing anti-icing system based on an operational amplifier, and in particular to a wide-range high-precision temperature conditioning circuit. Background Art

[0002] In the aviation field, the PT100 platinum resistance temperature sensor is widely used in an ambient temperature range of -60℃ to 300℃. When powered by a 1mA constant current source, its output voltage range is 76mV to 212mV. Because its output voltage range is in the millivolt level and its use environment is often different, the output temperature signal often contains noise, which is not conducive to the collection of temperature signals by test equipment. Therefore, it is necessary to design a conditioning circuit.

[0003] The traditional conditioning circuit is used to process the temperature range of -20℃~80℃, with an upper and lower range of about 100℃, so the accuracy requirement is low and it can be processed by a single-stage amplifier. However, such a conditioning circuit cannot process the temperature range of -60℃~300℃ to be processed by this application, so a specific solution is required. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a wide range and high precision temperature conditioning circuit, which can be used to process a wide temperature range with an upper and lower amplitude exceeding 300°C, and can be suitable for signal processing of PT100 platinum resistance temperature sensor.

[0005] The technical solution of the present invention:

[0006] A wide-range high-precision temperature conditioning circuit comprises a differential amplifier circuit and an isolation amplifier circuit; wherein the differential amplifier circuit is divided into a differential amplifier module and a subtraction module; after the temperature signal of a PT100 platinum resistance temperature sensor is filtered out of common-mode interference by the differential amplifier module, the subtraction module performs subtraction before secondary amplification to expand the acquisition range, and then sends it to the isolation amplifier circuit; the isolation amplifier circuit is divided into a common-phase proportional amplifier module and an isolation module; after the common-phase proportional amplifier module performs secondary amplification on the transmitted signal, the isolation module performs isolation and then sends it to a test device.

[0007] Furthermore, the differential amplifier module includes an operational amplifier N1A, a resistor R6, a resistor R7, a resistor R8 and a resistor R9. The positive signal output by the temperature sensor is connected to pin 3 of the operational amplifier N1A through the resistor R6, the negative signal output by the temperature sensor is connected to pin 2 of the operational amplifier N1A through the resistor R7, and pin 1 of the operational amplifier N1A is connected to its pin 2 through the resistor R8; pin 3 of the operational amplifier N1A is also grounded through the resistor R9; pins 4 and 11 of the operational amplifier N1A are respectively connected to the power supply.

[0008] Furthermore, the resistor R6 is 10KΩ, the resistor R7 is 10KΩ, the resistor R8 is 51KΩ, and the resistor R9 is 51KΩ. These four resistors are matched to obtain the amplification factor of the first stage.

[0009] Furthermore, the filtering structure of the differential amplifier module includes capacitors C1, C2, C3 and C4. The positive signal output by the temperature sensor is grounded before resistor R6 through capacitors C1 and C2 in parallel; the negative signal output by the temperature sensor is grounded before resistor R7 through capacitors C3 and C4 in parallel.

[0010] Further, the capacitor C1 is 0.1 μF, the capacitor C2 is 47 μF, the capacitor C3 is 0.1 μF, and the capacitor C4 is 47 μF. It is determined according to the amplitude of the analog voltage value of the PT100 platinum resistance temperature sensor.

[0011] Furthermore, the subtraction module includes resistors R10, R11, R12, R13, R14 and operational amplifier N1B; pin 1 of operational amplifier N1A is connected to pin 5 of operational amplifier N1B through resistor R10; pin 5 of operational amplifier N1B is also grounded through resistor R15; pin 6 of operational amplifier N1B is connected to a +5V reference voltage source through resistors R11 and R12 connected in series, and pin 6 of operational amplifier N1B is grounded through resistors R11 and R13 connected in series; pin 6 of operational amplifier N1B is also connected to pin 7 of connector through resistor R14; pins 4 and 11 of operational amplifier N1B are respectively connected to the power supply.

[0012] Furthermore, the resistor R10 is 43KΩ, the resistor R11 is 43KΩ, the resistor R12 is 47KΩ, the resistor R13 is 3KΩ, and the resistor R14 is 43KΩ. This design is for pre-processing before the second-stage voltage amplification, which can reduce the voltage and thus obtain a larger adjustment range.

[0013] Furthermore, the in-phase proportional amplifier module includes resistors R16, R17, R18 and operational amplifier N1C, pin 7 of operational amplifier N1B is connected to pin 10 of operational amplifier N1C via resistor R18, pin 9 of operational amplifier N1C is grounded via resistor R16, and pin 9 of operational amplifier N1C is also connected to pin 8 via resistor R17; pins 4 and 11 of operational amplifier N1C are respectively connected to the power supply.

[0014] Furthermore, the resistor R16 is 4KΩ, the resistor R17 is 10KΩ, and the resistor R18 is 5.1KΩ.

[0015] Furthermore, the isolation module includes a resistor R19, a voltage-stabilizing diode 1N5226, and a voltage follower N2A, wherein the resistor R19 is 10KΩ, the voltage follower N2A adopts F124, and the clamping voltage of the voltage-stabilizing diode 1N5226 is 3V.

[0016] The advantages of the present invention are as follows:

[0017] 1. The present invention is characterized in that the temperature conditioning circuit is designed based on a differential amplifier circuit, and has the characteristics of amplifying weak signals, filtering out clutter interference, isolating inputs and outputs, protecting test equipment, and having strong anti-interference capabilities.

[0018] 2. In the aviation field, the PT100 platinum resistance temperature sensor is widely used in an ambient temperature range of -60℃ to 300℃. Such a high temperature range often places high demands on the acquisition accuracy of the acquisition equipment. When the temperature sensor is powered by a 1mA constant current source, its output voltage range is 76mV to 212mV. Because its output voltage range is in the millivolt level, it is more difficult for the acquisition equipment to collect the temperature signal. By selecting the resistance values ​​of R6, R7, R8, and R9 in the differential amplifier circuit of this patent, and the resistance values ​​of R16, R17, and R18, the millivolt-level temperature signal is amplified in the first and second stages to meet the acquisition requirements of the acquisition equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-link diagram of the system of the present invention;

[0020] Figure 2 Differential amplifier circuit diagram;

[0021] Figure 3 Isolation amplifier circuit diagram. DETAILED DESCRIPTION

[0022] This section is an embodiment of the present invention, which is used to explain and illustrate the technical solution of the present invention.

[0023] A wide-range high-precision temperature conditioning circuit comprises a differential amplifier circuit and an isolation amplifier circuit; wherein the differential amplifier circuit is divided into a differential amplifier module and a subtraction module; after the temperature signal of a PT100 platinum resistance temperature sensor is filtered out of common-mode interference by the differential amplifier module, the subtraction module performs subtraction before secondary amplification to expand the acquisition range, and then sends it to the isolation amplifier circuit; the isolation amplifier circuit is divided into a common-phase proportional amplifier module and an isolation module; after the common-phase proportional amplifier module performs secondary amplification on the transmitted signal, the isolation module performs isolation and then sends it to a test device.

[0024] The differential amplifier module includes an operational amplifier N1A, a resistor R6, a resistor R7, a resistor R8 and a resistor R9. The positive signal output by the temperature sensor is connected to pin 3 of the operational amplifier N1A through the resistor R6, and the negative signal output by the temperature sensor is connected to pin 2 of the operational amplifier N1A through the resistor R7. Pin 1 of the operational amplifier N1A is connected to its pin 2 through the resistor R8; pin 3 of the operational amplifier N1A is also grounded through the resistor R9; pins 4 and 11 of the operational amplifier N1A are respectively connected to the power supply.

[0025] The resistor R6 is 10KΩ, the resistor R7 is 10KΩ, the resistor R8 is 51KΩ, and the resistor R9 is 51KΩ. These four resistors are matched to obtain the amplification factor of the first stage.

[0026] The filtering structure of the differential amplifier module includes capacitors C1, C2, C3 and C4. The positive signal output by the temperature sensor is grounded before the resistor R6 through the capacitors C1 and C2 connected in parallel; the negative signal output by the temperature sensor is grounded before the resistor R7 through the capacitors C3 and C4 connected in parallel.

[0027] Capacitor C1 is 0.1 μF, capacitor C2 is 47 μF, capacitor C3 is 0.1 μF, and capacitor C4 is 47 μF. It is determined according to the amplitude of the analog voltage value of the PT100 platinum resistance temperature sensor.

[0028] The subtraction module includes resistor R10, resistor R11, resistor R12, resistor R13, resistor R14 and operational amplifier N1B; pin 1 of operational amplifier N1A is connected to pin 5 of operational amplifier N1B through resistor R10; pin 5 of operational amplifier N1B is also grounded through resistor R15; pin 6 of operational amplifier N1B is connected to a +5V reference voltage source through resistor R11 and resistor R12 connected in series, and pin 6 of operational amplifier N1B is grounded through resistor R11 and resistor R13 connected in series; pin 6 of operational amplifier N1B is also connected to pin 7 of connector through resistor R14; pins 4 and 11 of operational amplifier N1B are respectively connected to power supplies.

[0029] The resistor R10 is 43KΩ, the resistor R11 is 43KΩ, the resistor R12 is 47KΩ, the resistor R13 is 3KΩ, and the resistor R14 is 43KΩ. This design is for pre-processing before the second-stage voltage amplification, which can reduce the voltage and obtain a larger adjustment range.

[0030] The in-phase proportional amplifier module includes resistors R16, R17, R18 and operational amplifier N1C. Pin 7 of operational amplifier N1B is connected to pin 10 of operational amplifier N1C through resistor R18, pin 9 of operational amplifier N1C is grounded through resistor R16, and pin 9 of operational amplifier N1C is also connected to pin 8 through resistor R17; pins 4 and 11 of operational amplifier N1C are respectively connected to power supplies.

[0031] The resistor R16 is 4KΩ, the resistor R17 is 10KΩ, and the resistor R18 is 5.1KΩ.

[0032] The isolation module includes a resistor R19, a voltage-stabilizing diode 1N5226 and a voltage follower N2A. Pin 9 of the operational amplifier N1C is connected to pin 3 of the voltage follower N2A through the resistor R19. Pins 2 and 1 of the voltage follower N2A are connected. Pin 1 of the voltage follower N2A is connected to a test device. Pin 1 of the voltage follower N2A is also grounded through the voltage-stabilizing diode 1N5226.

[0033] The voltage follower N2A uses F124, the clamping voltage of the voltage follower diode 1N5226 is 3V, the 4th and 11th pins of the voltage follower N2A are connected to a 5V power supply at one end, and the other end is grounded.

[0034] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings.

[0035] like Figure 1 As shown in the figure, the ambient temperature range of the wing anti-icing system is -60℃~300℃. When the PT100 platinum resistance temperature sensor is powered by a 1mA constant current source, its output voltage range is 76mV~212mV. Because its output voltage range is in the millivolt level, it is not conducive to the collection of temperature signals by test equipment. In addition, due to different operating environments, the output temperature signal often carries noise. A conditioning circuit is used to remove the common-mode interference signal in the temperature signal and amplify it to 304mV~2736mV, which is convenient for subsequent test equipment to collect. The conditioning circuit includes a differential amplifier circuit and an isolation amplifier circuit.

[0036] A temperature conditioning circuit, characterized in that:

[0037] It includes a differential amplifier circuit and an isolation amplifier circuit. The differential amplifier circuit mainly filters out the interference signal in the input temperature signal and performs primary amplification, and the isolation amplifier circuit performs secondary amplification on the preliminarily conditioned temperature signal and isolates the output signal from the input signal.

[0038] The input temperature signal is characterized in that: in the aviation field, the ambient temperature range of the widely used PT100 platinum resistance temperature sensor is -60°C to 300°C, and its output voltage range is 76mV to 212mV when powered by a 1mA constant current source. Because its output voltage range is in the millivolt level and its use environment is often different, the output temperature signal often has noise, which is not conducive to the collection of temperature signals by test equipment.

[0039] The differential amplifier circuit is characterized in that: the differential amplifier circuit is composed of an operational amplifier, a plurality of resistors and capacitors, and utilizes the symmetry of its own circuit to filter out common-mode interference, amplifies the input signal in one stage, and subtracts it from the reference voltage to output a preliminary conditioned voltage.

[0040] The isolation amplifier circuit is characterized in that: the isolation amplifier circuit is composed of an operational amplifier, a voltage follower, and a plurality of resistors, the preliminary conditioning voltage obtained in the differential amplifier circuit is amplified at the second level, and a voltage follower and a voltage regulator diode are used at the signal output end for isolation and protection.

[0041] like Figure 2 As shown, the differential amplifier circuit is composed of an operational amplifier FXOP11A, resistors R6 to R15, and capacitors C1 to C4. The temperature sensor outputs a temperature voltage signal with an amplitude range of 76mV to 212mV, where R6, R7, R8, R9 and N1A form a differential amplifier circuit, which uses the symmetry of its own circuit to filter out common-mode interference, amplifies the input signal by R9 / R6 = 5.1 times, and outputs a voltage range of 387mV to 1081mV at pin 1 of N1A. C1 to C4 complete the filtering of the input temperature signal. R12 and R13 form a voltage divider circuit, which divides the reference voltage 5V to obtain a reference voltage of 300mV. N1B, R10, R11, R14, and R15 form a subtraction circuit, which subtracts the output signal of pin 1 of N1A from the reference voltage 300mV and outputs a preliminary conditioned voltage of 87mV to 781mV at pin 7 of N1B.

[0042] like Figure 3 As shown in the figure, the isolation amplifier circuit is composed of an operational amplifier FXOP11A, a voltage follower F124, a voltage regulator diode 1N5226, and resistors R16 to R19. Among them, R16, R17, R18 and N1C form a common-phase proportional amplifier circuit. Figure 2 The preliminary conditioning voltage obtained is further amplified by R17 / (R16+R17)=3.5 times, and the output voltage range at pin 8 of N1C is 304mV~2736mV. The F124 voltage follower isolates the temperature conditioning signal output from the input, and the 1N5226 voltage regulator diode clamps the voltage to 3V, protecting the output signal from exceeding 3V and damaging the main control chip DSP in the test equipment.

Claims

1. A wide range and high precision temperature conditioning circuit, characterized in that: It includes a differential amplifier circuit and an isolation amplifier circuit; wherein the differential amplifier circuit is divided into a differential amplifier module and a subtraction module. After the temperature signal of the PT100 platinum resistance temperature sensor is filtered out of common-mode interference by the differential amplifier module, the subtraction module performs subtraction before secondary amplification to expand the acquisition range, and then sends it to the isolation amplifier circuit. The isolation amplifier circuit is divided into a common-phase proportional amplifier module and an isolation module. After the common-phase proportional amplifier module performs secondary amplification on the transmitted signal, the isolation module performs isolation and then sends it to the test equipment. The differential amplifier module includes an operational amplifier N1A, a resistor R6, a resistor R7, a resistor R8 and a resistor R9. The positive signal output by the temperature sensor is connected to the pin 3 of the operational amplifier N1A through the resistor R6, and the negative signal output by the temperature sensor is connected to the pin 2 of the operational amplifier N1A through the resistor R7. The pin 1 of the operational amplifier N1A is connected to its pin 2 through the resistor R8; the pin 3 of the operational amplifier N1A is also grounded through the resistor R9; the pins 4 and 11 of the operational amplifier N1A are respectively connected to the power supply; The subtraction module includes a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and an operational amplifier N1B; pin 1 of the operational amplifier N1A is connected to pin 5 of the operational amplifier N1B through the resistor R10; pin 5 of the operational amplifier N1B is also grounded through the resistor R15; pin 6 of the operational amplifier N1B is connected to a +5V reference voltage source through a series resistor R11 and a resistor R12, and pin 6 of the operational amplifier N1B is grounded through a series resistor R11 and a resistor R13; pin 6 of the operational amplifier N1B is also connected to pin 7 of the connector through the resistor R14; pins 4 and 11 of the operational amplifier N1B are respectively connected to the power supply; The in-phase proportional amplifier module includes a resistor R16, a resistor R17, a resistor R18 and an operational amplifier N1C, wherein the pin 7 of the operational amplifier N1B is connected to the pin 10 of the operational amplifier N1C through the resistor R18, the pin 9 of the operational amplifier N1C is grounded through the resistor R16, and the pin 9 of the operational amplifier N1C is also connected to its pin 8 through the resistor R17; the pins 4 and 11 of the operational amplifier N1C are respectively connected to the power supply; The isolation module includes a resistor R19, a voltage-stabilizing diode 1N5226 and a voltage follower N2A. Pin 9 of the operational amplifier N1C is connected to pin 3 of the voltage follower N2A through the resistor R19. Pins 2 and 1 of the voltage follower N2A are connected. Pin 1 of the voltage follower N2A is connected to a test device. Pin 1 of the voltage follower N2A is also grounded through the voltage-stabilizing diode 1N5226.

2. A wide range and high precision temperature conditioning circuit according to claim 1, characterized in that: The resistor R6 is 10KΩ, the resistor R7 is 10KΩ, the resistor R8 is 51KΩ, and the resistor R9 is 51KΩ.

3. A wide range and high precision temperature conditioning circuit according to claim 1, characterized in that: The filtering structure of the differential amplifier module includes capacitors C1, C2, C3 and C4. The positive signal output by the temperature sensor is grounded before the resistor R6 through the capacitors C1 and C2 connected in parallel; the negative signal output by the temperature sensor is grounded before the resistor R7 through the capacitors C3 and C4 connected in parallel.

4. A wide range and high precision temperature conditioning circuit according to claim 3, characterized in that: Capacitor C1 is 0.1 μF, capacitor C2 is 47 μF, capacitor C3 is 0.1 μF, and capacitor C4 is 47 μF.

5. A wide range and high precision temperature conditioning circuit according to claim 1, characterized in that: The resistor R10 is 43KΩ, the resistor R11 is 43KΩ, the resistor R12 is 47KΩ, the resistor R13 is 3KΩ, and the resistor R14 is 43KΩ.

6. A wide range and high precision temperature conditioning circuit according to claim 1, characterized in that: The resistor R16 is 4KΩ, the resistor R17 is 10KΩ, and the resistor R18 is 5.1KΩ.

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