A circuit for improving the accuracy of a pressure sensor signal

Abstract

The utility model discloses a kind of circuit of the improvement pressure sensor signal precision in the technical field of pressure sensor, including pressure sensor P, the 2 feet of pressure sensor P are connected with reference voltage circuit, reference voltage circuit is connected with feedback control circuit, the 4 feet of pressure sensor P are grounded, the 1 foot and 3 feet of pressure sensor P are connected with amplification circuit, amplification circuit is connected with filter circuit.Circuit is through pressure sensor and gathers physical quantity signal, signal is amplified by amplification circuit, and filtering is carried out by filter circuit, and reference voltage circuit cooperates feedback control circuit, can provide stable power supply current for pressure sensor, compensate temperature drift or power fluctuation, to improve measurement accuracy.

Description

Technical Field

[0001] This utility model relates to a current sampling circuit for new energy vehicles in the field of current sensor technology. Background Technology

[0002] Pressure measurement is a critical process in industrial control systems, and its accuracy and stability directly affect the system's functionality, performance, and reliability. Silicon strain gauge pressure sensors combine a silicon strain gauge with a stainless steel diaphragm to convert pressure into an electrical signal, offering advantages such as high sensitivity, fast dynamic response, good linearity, and corrosion resistance. However, the output signal of these pressure sensors is in the mV range, making them susceptible to external interference, which can affect their output accuracy. Utility Model Content

[0003] The purpose of this invention is to provide a circuit that improves the signal accuracy of a pressure sensor, thereby enhancing the output accuracy of the pressure sensor.

[0004] To achieve the above objectives, this utility model provides a circuit for improving the signal accuracy of a pressure sensor, including a pressure sensor P. Pin 2 of the pressure sensor P is connected to a reference voltage circuit, which is connected to a feedback control circuit. Pin 4 of the pressure sensor P is grounded. Pins 1 and 3 of the pressure sensor P are both connected to an amplifier circuit, which is connected to a filter circuit.

[0005] Compared with the prior art, the beneficial effects of this utility model are that the circuit collects physical quantity signals through a pressure sensor, amplifies the signals through an amplifier circuit, and filters them through a filter circuit. The reference voltage circuit, together with the feedback control circuit, can provide a stable power supply current for the pressure sensor, compensate for power fluctuations, and thus improve measurement accuracy.

[0006] As a further improvement of this utility model, the reference voltage circuit includes a reference voltage source V. ref Reference voltage source V ref The amplifier A1 is connected to pin 2. Pin 3 of the amplifier A1 is connected to one end of resistor R5 and one end of resistor R6. The other end of resistor R5 is grounded. The other end of resistor R6 is connected to pin 2 of pressure sensor P and the feedback control circuit. Pin 1 of the amplifier A1 is connected to the feedback control circuit.

[0007] Thus, the reference voltage V ref After being divided by R5 and R6, a stable reference voltage is provided for amplifier A1, ensuring that the zero-point drift of the amplifier circuit is minimized.

[0008] As a further improvement of this utility model, the feedback control circuit includes a resistor R7. One end of the resistor R7 is connected to pin 1 of the amplifier A1. The other end of the resistor R7 is connected to the base of transistor Q1 and the drain of NMOS transistor Q3. The emitter of transistor Q1 is connected to the other end of the resistor R6. The collector of transistor Q1 is connected to one end of resistor R0 and one end of resistor R8. The other end of resistor R0 is connected to the source of PMOS transistor Q2 and the power supply VDD. The gate of PMOS transistor Q2 is connected to the other end of resistor R8. The drain of PMOS transistor Q2 is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R10, one end of capacitor C1, and the gate of NMOS transistor Q3. The other end of resistor R10 is connected to the other end of capacitor C1 and grounded. The source of NMOS transistor Q3 is grounded.

[0009] In this way, amplifier A1 detects the working status of the pressure sensor and dynamically adjusts the output current of Q1~Q3 to provide a stable power supply current for the pressure sensor (through current limiting and biasing by R0, R8, R9, and R10), compensating for temperature drift or power fluctuations and improving measurement accuracy.

[0010] As a further improvement of this utility model, the amplifier circuit includes resistors R11 and R12. One end of resistor R11 is connected to pin 3 of pressure sensor P, one end of resistor R12 is connected to pin 1 of pressure sensor P, the other end of resistor R11 is connected to pin 2 of amplifier A2, and the other end of resistor R12 is connected to pin 3 of amplifier A2. The output voltage signal U1 is output from pin 1 of amplifier A2.

[0011] The resistance change of the pressure sensor P outputs a differential signal ΔV, which is then amplified by amplifier A2 to output an analog signal.

[0012] As a further improvement of this utility model, the filter circuit includes a capacitor C2. One end of the capacitor C2 is connected to one end of the capacitor C3, pin 2 of the amplifier A2, and the other end of the resistor R11. The other end of the capacitor C3 is grounded. The other end of the capacitor C2 is connected to one end of the capacitor C4, pin 3 of the amplifier A2, and the other end of the resistor R12. The other end of the capacitor C4 is grounded.

[0013] In this way, capacitors C2, C3, and C4 filter out high-frequency noise from the amplifier circuit, ensuring the stability of the output signal. Attached Figure Description

[0014] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings: like Figure 1The circuit shown is for improving the signal accuracy of a pressure sensor. It includes a pressure sensor P, pin 2 of the pressure sensor P is connected to a reference voltage circuit, the reference voltage circuit is connected to a feedback control circuit, pin 4 of the pressure sensor P is grounded, pins 1 and 3 of the pressure sensor P are both connected to an amplifier circuit, and the amplifier circuit is connected to a filter circuit.

[0016] The reference voltage circuit includes a reference voltage source V. ref The reference voltage source Vref is connected to pin 2 of amplifier A1. Pin 3 of amplifier A1 is connected to one end of resistor R5 and one end of resistor R6 respectively. The other end of resistor R5 is grounded. The other end of resistor R6 is connected to pin 2 of pressure sensor P and the feedback control circuit respectively. Pin 1 of amplifier A1 is connected to the feedback control circuit.

[0017] The feedback control circuit includes resistor R7. One end of resistor R7 is connected to pin 1 of amplifier A1. The other end of resistor R7 is connected to the base of transistor Q1 and the drain of NMOS transistor Q3. The emitter of transistor Q1 is connected to the other end of resistor R6. The collector of transistor Q1 is connected to one end of resistor R0 and one end of resistor R8. The other end of resistor R0 is connected to the source of PMOS transistor Q2 and the power supply VDD. The gate of PMOS transistor Q2 is connected to the other end of resistor R8. The drain of PMOS transistor Q2 is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R10, one end of capacitor C1, and the gate of NMOS transistor Q3. The other end of resistor R10 is connected to the other end of capacitor C1 and grounded. The source of NMOS transistor Q3 is grounded.

[0018] The amplifier circuit includes resistors R11 and R12. One end of resistor R11 is connected to pin 3 of pressure sensor P, and one end of resistor R12 is connected to pin 1 of pressure sensor P. The other end of resistor R11 is connected to pin 2 of amplifier A2, and the other end of resistor R12 is connected to pin 3 of amplifier A2. Amplifier A2 outputs voltage signal U1 from pin 1.

[0019] The filter circuit includes capacitor C2. One end of capacitor C2 is connected to one end of capacitor C3, pin 2 of amplifier A2, and the other end of resistor R11. The other end of capacitor C3 is grounded. The other end of capacitor C2 is connected to one end of capacitor C4, pin 3 of amplifier A2, and the other end of resistor R12. The other end of capacitor C4 is grounded.

[0020] In this invention, resistors R1, R2, R3, and R4 form a Wheatstone bridge. When the silicon strain gauge of the pressure sensor changes, its resistance changes, disrupting the bridge balance and generating a differential voltage signal proportional to the change in the physical quantity. Resistor R11 transmits the signal from bridge node 3 to the non-inverting input of amplifier A2, and resistor R12 provides a ground reference for the inverting input of amplifier A2, thus enabling single-ended amplification of the differential signal in conjunction with amplifier A2. Amplifier A2, acting as a differential amplifier, amplifies the weak differential signal (typically in the mV range) output from the Wheatstone bridge, outputting a measurable voltage signal U0. Capacitor C2 is connected in parallel at the input of amplifier A2 to filter out high-frequency noise in the bridge output signal, preventing interference with the amplifier circuit. Capacitors C3 and C4 are connected in parallel between the power supply terminal of amplifier A2 and ground to stabilize the power supply voltage and suppress the influence of power supply ripple on the amplifier circuit.

[0021] The circuit output voltage (serving as the constant voltage of the pressure sensor) is divided in series by resistors R5 and R6 and then fed back to pin 3 of amplifier A1 for comparison with the reference voltage Vref connected to pin 2. Amplifier A1 outputs an error control signal based on the difference between the feedback voltage and Vref, achieving closed-loop negative feedback regulation and stabilizing the system output. The output signal of amplifier A1 is current-limited by resistor R7 and then drives transistor Q1. Q1 amplifies the current to control the subsequent power transistors. Transistor Q1 receives the output signal from A1 through resistor R7. When A1 outputs a high level, Q1 saturates and conducts, lowering its collector potential and controlling PMOS transistor Q2 to turn off. When A1 outputs a low level, Q1 turns off, and VDD provides a high voltage to the gate of Q2 through R0 and R8, turning Q2 on. This, in turn, causes the gate of Q3 to receive a bias voltage through R9 and turn on. R10 is the source sampling resistor for Q3. If the current is too large, the voltage across R10 increases, limiting the current of Q3 through feedback and achieving overcurrent protection. C1 filters out high-frequency interference from the gate of Q3, stabilizing its operating state. Resistors R0, R8, and R9 are current-limiting resistors to prevent Q2 and Q3 from being damaged by overcurrent. C1 and R10 form an RC snubber circuit to suppress voltage spikes generated during the switching process of Q3, protecting the power transistors.

[0022] This invention acquires physical quantity signals through a pressure sensor, amplifies the signals through an amplifier circuit, and filters them through a filter circuit. The reference voltage circuit, in conjunction with the feedback control circuit, can provide a stable power supply current to the pressure sensor, compensate for power fluctuations, and thus improve measurement accuracy.

[0023] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. A circuit for improving the signal accuracy of a pressure sensor, characterized in that: It includes a pressure sensor P, pin 2 of which is connected to a reference voltage circuit, which is connected to a feedback control circuit. Pin 4 of the pressure sensor P is grounded, and pins 1 and 3 of the pressure sensor P are both connected to an amplifier circuit, which is connected to a filter circuit.

2. The circuit for improving the signal accuracy of a pressure sensor according to claim 1, characterized in that: The reference voltage circuit includes a reference voltage source V. ref The reference voltage source Vref is connected to pin 2 of amplifier A1. Pin 3 of amplifier A1 is connected to one end of resistor R5 and one end of resistor R6 respectively. The other end of resistor R5 is grounded. The other end of resistor R6 is connected to pin 2 of pressure sensor P and the feedback control circuit respectively. Pin 1 of amplifier A1 is connected to the feedback control circuit.

3. The circuit for improving the signal accuracy of a pressure sensor according to claim 2, characterized in that: The feedback control circuit includes resistor R7. One end of resistor R7 is connected to pin 1 of amplifier A1. The other end of resistor R7 is connected to the base of transistor Q1 and the drain of NMOS transistor Q3. The emitter of transistor Q1 is connected to the other end of resistor R6. The collector of transistor Q1 is connected to one end of resistor R0 and one end of resistor R8. The other end of resistor R0 is connected to the source of PMOS transistor Q2 and the power supply VDD. The gate of PMOS transistor Q2 is connected to the other end of resistor R8. The drain of PMOS transistor Q2 is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R10, one end of capacitor C1, and the gate of NMOS transistor Q3. The other end of resistor R10 is connected to the other end of capacitor C1 and grounded. The source of NMOS transistor Q3 is grounded.

4. The circuit for improving the accuracy of a pressure sensor signal according to claim 3, characterized in that: The amplifier circuit includes resistors R11 and R12. One end of resistor R11 is connected to pin 3 of pressure sensor P, and one end of resistor R12 is connected to pin 1 of pressure sensor P. The other end of resistor R11 is connected to pin 2 of amplifier A2, and the other end of resistor R12 is connected to pin 3 of amplifier A2. Amplifier A2 outputs voltage signal U1 from pin 1.

5. The circuit for improving the signal accuracy of a pressure sensor according to claim 4, characterized in that: The filter circuit includes capacitor C2. One end of capacitor C2 is connected to one end of capacitor C3, pin 2 of amplifier A2, and the other end of resistor R11. The other end of capacitor C3 is grounded. The other end of capacitor C2 is connected to one end of capacitor C4, pin 3 of amplifier A2, and the other end of resistor R12. The other end of capacitor C4 is grounded.

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