Three-wire platinum resistor signal acquisition circuit based on double operational amplifier constant current source

Abstract

The utility model belongs to the technical field of aviation electrical, and particularly relates to a three-wire platinum resistor signal acquisition circuit based on a double-operational-amplifier constant current source. The circuit converts the resistance change of the platinum resistance sensor into a voltage signal, and amplifies the voltage signal as the difference between the input (+) and the input (-) of the operational amplifier. The system has the advantages of low lead resistance, high resolution, reliable signal acquisition and simple module debugging.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the aviation electrical technology field, concretely relates to a three -wire system platinum resistance signal collection circuit based on double operational amplifier constant current source. BACKGROUND

[0002] Due to the need of monitoring and controlling various parameters, a large number of platinum resistance sensors are arranged at different positions on the aircraft by the environmental control system on the aircraft, and the environmental control system controller controls relevantly by collecting a large number of temperature signals of the platinum resistance sensors. The current constant current source platinum resistance signal high-precision collection method has low resolution and complex module debugging due to the lead resistance. UTILITY MODEL CONTENT

[0003] The utility model discloses a three -wire system platinum resistance signal collection circuit based on double operational amplifier constant current source, which is provided for the problems of low resolution and complex module debugging in the existing constant current source platinum resistance signal collection method, and the constant current source debugging module and three -wire system platinum resistance signal collection amplification module are built by the operational amplifier, the connection mode of the platinum resistance sensor is designed as three -wire system for the problem of large lead resistance of the platinum resistance sensor, so that the voltage signal after the temperature signal of the platinum resistance sensor is converted can be directly used as the amplification value of the operational amplifier, the accurate conversion of the platinum resistance sensor signal is realized, and the efficiency of module debugging is greatly improved.

[0004] TECHNICAL SCHEME

[0005] A three -wire system platinum resistance signal collection circuit based on double operational amplifier constant current source, comprising: platinum resistance sensor, constant current source generation circuit, amplification circuit, resistance Ra, wherein the A line of platinum resistance sensor is connected with the one end of resistance Ra and the inverting input end of amplification circuit, and the other end of resistance Ra is grounded;The B line of platinum resistance sensor is connected with the output I_b of constant current source generation circuit;The C line of platinum resistance sensor is connected with the noninverting input end of amplification circuit;The output end of amplification circuit is used as the output end of three -wire system platinum resistance signal collection circuit.

[0006] Further, the platinum resistance sensor is PT1000.

[0007] Further, the constant current source generation circuit comprises: an operational amplifier M1, an operational amplifier M2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor Rref, wherein, one end of the resistor R3 and one end of the resistor R4 are connected to the non-inverting input terminal of the operational amplifier M1; the other end of the resistor R3 is connected to the reference voltage Rref; one end of the resistor R1 and one end of the resistor R2 are connected to the inverting input terminal of the operational amplifier M1; the other end of the resistor R1 is grounded; the output terminal of the operational amplifier M1 is connected to the other end of the resistor R2 and one end of the resistor Rref; the other end of the resistor Rref is connected to the non-inverting input terminal of the operational amplifier M2, and the output current I_b of the operational amplifier M2 is connected to the inverting input terminal of the operational amplifier M2.

[0008] Further, the amplification circuit comprises: an operational amplifier M3, a resistor R5, a capacitor C1 and a capacitor C2, wherein, the two gain adjustment pins of the operational amplifier M3 are connected to the two ends of the resistor R5; one end of the capacitor C2 is connected to the positive power supply terminal of the operational amplifier M3, and the other end of the capacitor C2 and one end of the capacitor C1 are grounded; the reference terminal of the operational amplifier M3 is grounded; and the other end of the capacitor C1 is connected to the negative power supply terminal of the operational amplifier M3.

[0009] Further, the output I_b of the constant current source generation circuit is equal to the reference voltage Vref divided by the reference resistor Rref.

[0010] Further, the output Uout of the amplification circuit satisfies: Uout=(Uc-Ua)*(49.4KΩ / R5+1).

[0011] Beneficial effects:

[0012] The three-wire platinum resistance signal acquisition circuit based on the dual-operational-amplifier constant current source has the advantages that, in view of the problem of large lead resistance of the platinum resistance sensor, the connection mode of the platinum resistance sensor is designed as three-wire, so that the voltage signal converted from the temperature signal of the platinum resistance sensor can be directly used as the amplification value of the operational amplifier, precise conversion of the platinum resistance sensor signal is realized, and the efficiency of module debugging is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a three-wire platinum resistance signal acquisition circuit principle diagram based on a dual-operational-amplifier constant current source;

[0014] Figure 2 is a constant current source generation circuit diagram;

[0015] Figure 3 is a diagram of a platinum resistance sensor, a resistor Ra and an amplification circuit. DETAILED DESCRIPTION

[0016] The utility model discloses a three -wire system platinum resistance signal acquisition circuit based on double operational amplifier constant current source, in view of the problem of the lead resistance of platinum resistance sensor, the connection mode of platinum resistance sensor is designed as three -wire system, can directly take the amplified value of operational amplifier as the voltage signal of platinum resistance sensor temperature signal conversion, realizes the accurate conversion of platinum resistance sensor signal, improves the efficiency of module debugging greatly

[0017] The utility model is in detail below combining with the drawing and specific embodiment.

[0018] Figure 1 As shown in the three -wire system platinum resistance signal acquisition circuit based on double operational amplifier constant current source. For the external platinum resistance sensor, the connection mode is three -wire system, generates constant current source, converts the resistance change of platinum resistance sensor into voltage signal, and the voltage signal is amplified as the difference of operational amplifier input (+) and input (-).

[0019] Figure 2 Constant current source generation circuit, Figure 3 It is the drawing of platinum resistance sensor, resistance Ra and amplification circuit. A three -wire system platinum resistance signal acquisition circuit based on double operational amplifier constant current source forms stable constant current source signal I_b with the same specification operational amplifier M1 and M2, the same specification resistance R1 and R2, the same specification resistance R3 and R4, reference voltage Vref, reference resistance Rref;Different constant current source signals I_b can be realized by setting different reference voltages Vref and reference resistances Rref;The voltage difference formed by inputting the constant current source signal I_b to the platinum resistance sensor is amplified by the operational amplifier.

[0020] In the constant current source generation circuit, the inverting input end of operational amplifier M1 is connected with the common end of resistance R1 and R2, the other end of resistance R1 is grounded, and the other end of resistance R2 is connected with the output end of operational amplifier M1;The noninverting input end of operational amplifier M1 is connected with the common end of resistance R3 and R4, the other end of resistance R3 is connected with reference voltage Vref, and the other end of resistance R4 is connected with the output end of operational amplifier M2;The power supply negative end of operational amplifier M1 is connected with-15V;The output end of operational amplifier M1 is connected with the common end of resistance R2 and Rref, the other end of resistance Rref is connected with the noninverting input end of operational amplifier M2;The power supply positive end of operational amplifier M1 is connected with +15V. The inverting input end of operational amplifier M2 is connected with the output end;The noninverting input end of operational amplifier M2 outputs constant current source signal I_b;The power supply negative end of operational amplifier M2 is connected with-15V;The power supply positive end of operational amplifier M2 is connected with +15V.

[0021] As Figure 3A first gain adjusting pin of the operational amplifier M3 is connected with one end of the resistor R5, and the other end of the resistor R5 is connected with a second gain adjusting pin of the operational amplifier M3; an inverting input end of the operational amplifier M3 is connected with an A line of the platinum resistance sensor; a non-inverting input end of the operational amplifier M3 is connected with a C end of the platinum resistance sensor; a power supply negative end of the operational amplifier M3 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is grounded; a reference end of the operational amplifier M3 is grounded; an output end of the operational amplifier M3 outputs a conditioned and amplified signal U_out; a power supply positive end of the operational amplifier M3 is connected with one end of the capacitor C2, and the other end of the capacitor C2 is grounded; one end of a reference resistor Rref is connected with the A line of the platinum resistance sensor, and the other end of the reference resistor Rref is grounded.

Claims

1. A three-wire platinum resistance signal acquisition circuit based on a dual operational amplifier constant current source, characterized in that, The application relates to a three-wire platinum resistance sensor signal acquisition circuit. The platinum resistance sensor, a constant current source generation circuit, an amplification circuit and a resistance Ra are connected in series. The A line of the platinum resistance sensor is connected with one end of the resistance Ra and the inverting input end of the amplification circuit, and the other end of the resistance Ra is grounded; the B line of the platinum resistance sensor is connected with the output I_b of the constant current source generation circuit; the C line of the platinum resistance sensor is connected with the non-inverting input end of the amplification circuit; and the output end of the amplification circuit is used as the output end of the three-wire platinum resistance signal acquisition circuit.

2. The three-wire platinum resistance signal acquisition circuit based on dual operational amplifier constant current source according to claim 1, characterized in that, The platinum resistance sensor is PT1000.

3. The three-wire platinum resistance signal acquisition circuit based on dual operational amplifier constant current source according to claim 2, characterized in that, The constant current source generation circuit comprises an operational amplifier M1, an operational amplifier M2, a resistance R1, a resistance R2, a resistance R3, a resistance R4 and a resistance Rref. The non-inverting input end of the operational amplifier M1 is connected with one end of the resistance R3 and one end of the resistance R4; the other end of the resistance R3 is connected with a reference voltage Rref; the inverting input end of the operational amplifier M1 is connected with one end of the resistance R1 and one end of the resistance R2; the other end of the resistance R1 is grounded; the output end of the operational amplifier M1 is connected with the other end of the resistance R2 and one end of the resistance Rref; the non-inverting input end of the operational amplifier M2 is connected with the other end of the resistance Rref and outputs a current I_b; and the inverting input end of the operational amplifier M2 is connected with the other end of the resistance R4 and the output end of the operational amplifier M2.

4. The three-wire platinum resistance signal acquisition circuit based on dual operational amplifier constant current source according to claim 3, characterized in that, The amplification circuit comprises an operational amplifier M3, a resistance R5, a capacitor C1 and a capacitor C2. The two gain adjustment pins of the operational amplifier M3 are connected with the two ends of the resistance R5 respectively. One end of the capacitor C2 is connected with the positive power supply end of the operational amplifier M3, and the other end of the capacitor C2 and one end of the capacitor C1 are grounded. The reference end of the operational amplifier M3 is grounded, and the other end of the capacitor C1 is connected with the negative power supply end of the operational amplifier M3.

5. The three-wire platinum resistance signal acquisition circuit based on dual operational amplifier constant current source according to claim 4, characterized in that, The output I_b of the constant current source generation circuit is equal to the reference voltage Vref divided by the reference resistance Rref.

6. The three-wire platinum resistance signal acquisition circuit based on dual operational amplifier constant current source according to claim 5, characterized in that, The output Uout of the amplification circuit satisfies Uout=(Uc-Ua)*(49.4KΩ / R5+1).

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