IEPE circuit based on charge amplifier

Abstract

The utility model relates to the technical field of circuit design, in particular to an IEPE circuit based on a charge amplifier, which comprises a piezoelectric component, an input network, a voltage type amplifier, a feedback network and a constant current source circuit, the voltage component is connected in series with the voltage type amplifier, the input network is connected in parallel with the voltage component, and the feedback network is connected in parallel with the constant current source circuit. The feedback network is connected with the voltage type amplifier in parallel, the constant current source circuit is connected with the voltage type amplifier in series, the charge amplifier design is adopted, charge signals generated by the piezoelectric assembly are directly processed, the problem that low-frequency signals are insufficiently amplified in the traditional voltage type design is solved, and the low-frequency signal amplification efficiency is improved. Therefore, the sensitivity and the accuracy of the sensor in low-frequency vibration measurement are remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of circuit design especially relates to a IEPE circuit based on charge amplifier. BACKGROUND

[0002] IEPE sensor is widely used in the measurement of physical quantities such as vibration, impact and pressure due to its built-in amplifier circuit and constant current source power supply characteristics. However, the traditional IEPE sensor generally adopts voltage output design, mainly generates charge signals through piezoelectric elements, and outputs voltage signals after circuit processing. Although this design has high use convenience, it still has certain limitations in complex measurement environment. First, the traditional IEPE sensor lacks charge amplifier, and its low-frequency performance is poor, which is not sensitive enough in the measurement of low-frequency vibration signals, resulting in the accuracy of the measurement results being affected. In addition, the existing IEPE sensor has limited anti-interference ability in complex environment, especially in long-distance signal transmission or high electromagnetic interference environment, which may cause signal distortion or even loss. Therefore, some IEPE sensors based on charge amplifier are proposed to improve the sensitivity and low-frequency response of the signal. However, these sensors generally do not have constant current source design and cannot provide stable current drive, which not only limits the stability of signal transmission, but also fails to significantly improve the anti-interference ability. At the same time, the optimization of feedback network and input network in the circuit design is insufficient, which makes it difficult to further improve the measurement accuracy and reliability. Therefore, the existing IEPE sensor cannot effectively balance the charge amplification function, constant current source power supply and anti-interference performance, and needs to be improved. This patent combines the advantages of charge amplifier and constant current source circuit, optimizes the input network and feedback network design, aiming to improve the low-frequency response ability, signal stability and anti-interference performance of the sensor, and meet the demand of high-precision measurement in complex environment. SUMMARY

[0003] The utility model discloses to solve the problem that the traditional IEPE sensor lacks charge amplifier and leads to insufficient low-frequency performance, and the IEPE sensor with charge amplification function does not have constant current source design, and the signal transmission stability is poor and the anti-interference ability is insufficient in complex environment, and proposes a IEPE circuit based on charge amplifier.

[0004] The utility model discloses the following technical scheme realizes:

[0005] A kind of IEPE circuit based on charge amplifier, including piezoelectric component, input network, voltage amplifier, feedback network and constant current source circuit, the piezoelectric component is connected in series with the voltage amplifier, the input network is connected in parallel with the piezoelectric component, the feedback network is connected in parallel with the voltage amplifier, the constant current source circuit is connected in series with the voltage amplifier.

[0006] Further, the piezoelectric component is ceramic crystal Y1, the voltage type amplifier is operational amplifier U1, one end of the ceramic crystal Y1 is connected with the inverting input terminal of the operational amplifier U1, and the other end of the ceramic crystal Y1 is connected with the non-inverting input terminal of the operational amplifier U1 and then grounded.

[0007] Further, the input network comprises input capacitor C1 and input conductance G1, one end of the input capacitor C1 is connected with one end of the ceramic crystal, one end of the input conductance G1, the inverting input terminal of the operational amplifier U1 and the feedback network respectively, and the other end of the input capacitor C1 is connected with the other end of the ceramic crystal, the other end of the input conductance G1, the non-inverting input terminal of the operational amplifier U1 and then grounded.

[0008] Further, the feedback network comprises feedback capacitor C2 and feedback conductance G2, one end of the feedback capacitor C2 is connected with one end of the ceramic crystal Y1, one end of the feedback conductance G2, one end of the input capacitor C1, one end of the input conductance G1 and the inverting input terminal of the operational amplifier U1 respectively, and the other end of the feedback capacitor C2 is connected with the other end of the feedback conductance G2, the output terminal of the operational amplifier U1 and the constant current source circuit respectively.

[0009] Further, the constant current source circuit comprises a voltage detector, a constant current diode D1, a direct current power supply and a pull-down resistor R1, the positive electrode of the voltage detector is connected with the output terminal of the operational amplifier U1, the cathode of the constant current diode D1 and one end of the pull-down resistor R1 respectively, the anode of the constant current diode D1 is connected with the positive electrode of the direct current power supply, and the negative electrode of the direct current power supply is connected with the negative electrode of the voltage detector, the output terminal of the operational amplifier U1 and the other end of the pull-down resistor R1 respectively.

[0010] Further, the constant current source circuit further comprises a coupling capacitor C3, one end of the coupling capacitor C3 is connected with the cathode of the constant current diode D1, the other end of the coupling capacitor C3 is connected with one end of the pull-down resistor R1, and the other end of the pull-down resistor R1 is connected with the negative electrode of the voltage detector, the output terminal of the operational amplifier U1 and the negative electrode of the direct current power supply respectively.

[0011] Further, the constant current source circuit further comprises a coupling capacitor C3, one end of the coupling capacitor C3 is connected with the cathode of the constant current diode D1, the other end of the coupling capacitor C3 is connected with one end of the pull-down resistor R1, and the other end of the pull-down resistor R1 is connected with the negative electrode of the voltage detector, the output terminal of the operational amplifier U1 and the negative electrode of the direct current power supply respectively.

[0012] The utility model discloses a kind of IEPE circuits based on charge amplifier, by using charge amplifier design, directly processing the charge signal generated by piezoelectric component, avoid the problem of insufficient low-frequency signal amplification in traditional voltage type design, to significantly improve the sensitivity and accuracy of sensor in low-frequency vibration measurement.

[0013] (1) the utility model provides an IEPE circuit based on charge amplifier, by using charge amplifier design, directly processing the charge signal generated by piezoelectric component, avoid the problem of insufficient low-frequency signal amplification in traditional voltage type design, to significantly improve the sensitivity and accuracy of sensor in low-frequency vibration measurement.

[0014] (2) The utility model provides a kind of IEPE circuit based on charge amplifier, provide stable current drive in combination with constant current source circuit, ensure the consistency and reliability of signal in transmission process, especially applicable to long distance signal transmission scene;

[0015] (3) The utility model provides a kind of IEPE circuit based on charge amplifier, effectively suppresses external electromagnetic interference by the design of constant current source circuit and filter network, improves the purity and stability of signal output, so that sensor can maintain accurate measurement in complex electromagnetic environment;

[0016] (4) The utility model provides a kind of IEPE circuit based on charge amplifier, further improves the signal processing capacity of system and dynamic response performance of circuit by the reasonable configuration of input network and feedback network, ensures the accuracy and linearity of output signal;

[0017] (5) The utility model provides a kind of IEPE circuit based on charge amplifier, piezoelectric assembly, charge amplifier, constant current source and filter network are organically combined in overall circuit design, compact structure, convenient for integration into various measurement systems, adapt to a variety of practical application needs. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical scheme in the embodiments of the utility model, the drawings needed to be used in the embodiment description will be briefly introduced, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to these drawings without creative labor for ordinary skilled in the art.

[0019] Figure 1 The utility model provides a kind of IEPE circuit based on charge amplifier's circuit schematic diagram. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantage of the utility model more clearly, the utility model is further explained in detail in the following with example and drawing, the illustrative embodiment of the utility model and its explanation are only used to explain the utility model, and not as the limitation of the utility model.

[0021] Example 1

[0022] The embodiment proposes a kind of IEPE circuit based on charge amplifier, including piezoelectric assembly, input network, voltage amplifier, feedback network and constant current source circuit, improve the low-frequency response capability of sensor, anti-interference performance and the stability of signal transmission by optimizing the structure design and connection mode of each component.

[0023] An IEPE circuit based on charge amplifier, comprising a piezoelectric component, an input network, a voltage amplifier, a feedback network and a constant current source circuit, the piezoelectric component is connected in series with the voltage amplifier, the input network is connected in parallel with the piezoelectric component, the feedback network is connected in parallel with the voltage amplifier, and the constant current source circuit is connected in series with the voltage amplifier.

[0024] The piezoelectric component is ceramic crystal Y1, the voltage amplifier is operational amplifier U1, one end of the ceramic crystal Y1 is connected to the inverting input terminal of the operational amplifier U1, and the other end of the ceramic crystal Y1 is connected to the non-inverting input terminal of the operational amplifier U1 and then grounded.

[0025] The input network includes input capacitor C1 and input conductance G1, one end of the input capacitor C1 is connected to one end of the ceramic crystal, one end of the input conductance G1, the inverting input terminal of the operational amplifier U1 and the feedback network respectively, and the other end of the input capacitor C1 is connected to the other end of the ceramic crystal, the other end of the input conductance G1, the non-inverting input terminal of the operational amplifier U1 and then grounded respectively.

[0026] The feedback network includes feedback capacitor C2 and feedback conductance G2, one end of the feedback capacitor C2 is connected to one end of the ceramic crystal Y1, one end of the feedback conductance G2, one end of the input capacitor C1, one end of the input conductance G1 and the inverting input terminal of the operational amplifier U1 respectively, and the other end of the feedback capacitor C2 is connected to the other end of the feedback conductance G2, the output terminal of the operational amplifier U1 and the constant current source circuit respectively. The constant current source circuit includes a voltage detector, a constant current diode D1, a DC power supply and a pull-down resistor R1, the positive electrode of the voltage detector is connected to the output terminal of the operational amplifier U1, the cathode of the constant current diode D1 and one end of the pull-down resistor R1 respectively, the anode of the constant current diode D1 is connected to the positive electrode of the DC power supply, and the negative electrode of the DC power supply is connected to the negative electrode of the voltage detector, the output terminal of the operational amplifier U1 and the other end of the pull-down resistor R1 respectively. The constant current source circuit further includes a coupling capacitor C3, one end of the coupling capacitor C3 is connected to the cathode of the constant current diode D1, the other end of the coupling capacitor C3 is connected to one end of the pull-down resistor R1, and the other end of the pull-down resistor R1 is connected to the negative electrode of the voltage detector, the output terminal of the operational amplifier U1 and the negative electrode of the DC power supply respectively.

[0027] It also includes a filter network, the filter network includes a bypass capacitor C4, one end of the bypass capacitor C4 is connected to the cathode of the constant current diode D1, and the other end of the bypass capacitor C4 is connected to the negative electrode of the DC power supply.

[0028] The core function of the IEPE sensor in this embodiment is to convert mechanical vibration signals into electrical signals and amplify and process them. The specific working process is as follows:

[0029] The piezoelectric component (ceramic crystal Y1) as the core sensitive element generates an electric charge signal proportional to the vibration intensity when subjected to external mechanical vibration. One end of the ceramic crystal Y1 is connected to the inverting input terminal of the operational amplifier U1, and the other end is grounded through the non-inverting input terminal, ensuring effective transmission and isolation of the signal. The input network is composed of an input capacitor C1 and an input conductance G1, which are used for preliminary coupling and guiding of the electric charge signal. One end of the input capacitor C1 is connected to the ceramic crystal, the feedback network, and the inverting input terminal of the operational amplifier U1, respectively; the other end is connected to the other end of the ceramic crystal and the non-inverting input terminal of the operational amplifier U1. The input network is used to avoid signal distortion and provides stable input conditions for subsequent signal processing.

[0030] The operational amplifier U1 is responsible for converting the input electric charge signal into a voltage signal and amplifying it. The feedback network includes a feedback capacitor C2 and a feedback conductance G2, which can adjust the circuit gain and signal dynamic range, stabilize the working state of the amplifier, and realize closed-loop control through feedback. The feedback capacitor C2 is connected between the piezoelectric component and the inverting input terminal of the operational amplifier U1, and the other end is connected to the output terminal of the operational amplifier.

[0031] The present embodiment proposes a method for IEPE conversion using the principle of charge amplifier. After the piezoelectric component (such as ceramic crystal Y1) is subjected to mechanical vibration, it generates an electric charge signal proportional to the vibration intensity due to the piezoelectric effect. These high-impedance electric charge signals are introduced into the inverting input terminal of the operational amplifier U1 through the input network. The operational amplifier U1 and the feedback capacitor C2 form a closed-loop circuit, which converts the electric charge signal into a voltage signal and outputs a voltage The expression of the output voltage is:

[0032]

[0033] wherein, Q is the amount of electric charge generated by the piezoelectric component, C is the feedback capacitance value.

[0034] Through the optimized design of the input capacitor C1 and the feedback network, the conversion efficiency and accuracy of the electric charge signal are significantly improved.

[0035] The constant current source circuit is composed of a voltage detector, a constant current diode D1, a DC power supply, and a pull-down resistor R1, which provides stable current power supply for the sensor. The anode of the constant current diode D1 is connected to the positive electrode of the DC power supply, and the cathode is connected to the pull-down resistor R1 through the coupling capacitor C3. The other end of the pull-down resistor R1 is connected to the negative electrode of the voltage detector and the output terminal of the operational amplifier U1. The design of the constant current source circuit not only improves the power supply stability of the sensor, but also greatly improves its anti-interference ability.

[0036] The filter network comprises a bypass capacitor C4 connected between the cathode of the constant current diode D1 and the negative pole of the DC power supply for suppressing power supply noise and high frequency interference.

[0037] The voltage signal after final processing is output from the output terminal of the operational amplifier U1, which is proportional to the mechanical vibration detected by the piezoelectric assembly, and the output signal can be directly used for data acquisition equipment or subsequent analysis system, meeting the demand for high-precision vibration measurement in industrial or scientific research fields.

[0038] Embodiment 2

[0039] This embodiment proposes an IEPE circuit optimization method based on a charge amplifier on the basis of embodiment 1.

[0040] In this embodiment, the feedback network is optimized to expand the linear working range of the sensor and avoid nonlinear distortion. Specifically, a feedback inductor L1 is connected in parallel across the feedback capacitor C2. The presence of the feedback inductor L1 can compensate for signals of specific frequencies and improve linearity. One end of the inductor L1 is connected to one end of the feedback capacitor C2, and the other end is connected to the other end of the feedback capacitor C2.

[0041] In this embodiment, a temperature compensation circuit is added to improve stability under changes in ambient temperature. Specifically, a temperature sensor T1 (such as an NTC thermistor) is added to the compensation circuit. The temperature sensor T1 comprises an NTC thermistor. The temperature sensor detects changes in ambient temperature, and the compensation signal can be adjusted by adjusting the values of the feedback resistor or the input resistor.

[0042] The temperature sensor T1 is connected in series with an adjustable resistor, and the node after the series connection is connected to one end of the feedback conductance G2, for real-time adjustment of the feedback signal.

[0043] In this embodiment, an output model conditioning circuit is added to improve the driving capability of the output signal and adapt to the input requirements of subsequent equipment. Specifically, a voltage follower is added as a buffer. The voltage follower comprises an operational amplifier U2, which is connected as a voltage follower to isolate the influence of the load on the sensor. The input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U1, and the output terminal of the operational amplifier U2 serves as the final output terminal of the sensor.

[0044] The basic principle and main features of the utility model and the advantages of the utility model are shown and described above. The skilled in the art should understand that the utility model is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model can also have various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A charge amplifier-based IEPE circuit, characterized by, The piezoelectric component is connected in series with the voltage amplifier, the input network is connected in parallel with the piezoelectric component, the feedback network is connected in parallel with the voltage amplifier, and the constant current source circuit is connected in series with the voltage amplifier.

2. The IEPE circuit based on a charge amplifier according to claim 1, characterized in that, The piezoelectric component is a ceramic crystal Y1, and the voltage amplifier is an operational amplifier U1. One end of the ceramic crystal Y1 is connected to the inverting input terminal of the operational amplifier U1, and the other end of the ceramic crystal Y1 is connected to the non-inverting input terminal of the operational amplifier U1 and then grounded.

3. The IEPE circuit based on a charge amplifier according to claim 1, characterized in that, The input network includes an input capacitor C1 and an input conductance G1. One end of the input capacitor C1 is connected to one end of the ceramic crystal, one end of the input conductance G1, the inverting input terminal of the operational amplifier U1, and the feedback network, respectively. The other end of the input capacitor C1 is connected to the other end of the ceramic crystal, the other end of the input conductance G1, the non-inverting input terminal of the operational amplifier U1, and then grounded.

4. The IEPE circuit based on a charge amplifier according to claim 1, characterized in that, The feedback network includes a feedback capacitor C2 and a feedback conductance G2. One end of the feedback capacitor C2 is connected to one end of the ceramic crystal Y1, one end of the feedback conductance G2, one end of the input capacitor C1, one end of the input conductance G1, and the inverting input terminal of the operational amplifier U1, respectively. The other end of the feedback capacitor C2 is connected to the other end of the feedback conductance G2, the output terminal of the operational amplifier U1, and the constant current source circuit.

5. The IEPE circuit based on a charge amplifier according to claim 1, characterized in that, The constant current source circuit includes a voltage detector, a constant current diode D1, a DC power supply, and a pull-down resistor R1. The positive electrode of the voltage detector is connected to the output terminal of the operational amplifier U1, the cathode of the constant current diode D1, and one end of the pull-down resistor R1, respectively. The anode of the constant current diode D1 is connected to the positive electrode of the DC power supply. The negative electrode of the DC power supply is connected to the negative electrode of the voltage detector, the output terminal of the operational amplifier U1, and the other end of the pull-down resistor R1, respectively.

6. The IEPE circuit based on a charge amplifier according to claim 5, characterized in that, The constant current source circuit further includes a coupling capacitor C3. One end of the coupling capacitor C3 is connected to the cathode of the constant current diode D1. The other end of the coupling capacitor C3 is connected to one end of the pull-down resistor R1. The other end of the pull-down resistor R1 is connected to the negative electrode of the voltage detector, the output terminal of the operational amplifier U1, and the negative electrode of the DC power supply, respectively.

7. The IEPE circuit based on a charge amplifier according to claim 5, characterized in that, The filter network includes a bypass capacitor C4. One end of the bypass capacitor C4 is connected to the cathode of the constant current diode D1. The other end of the bypass capacitor C4 is connected to the negative electrode of the DC power supply.

Images