A shock saturated vibration signal conditioning circuit

Abstract

The application provides a kind of impact saturated vibration signal conditioning circuit, for and PE vibration sensor connection, comprising: differential input charge-voltage conversion circuit, band-pass filter circuit, integration circuit, effective value conversion circuit, power supply and 4-20mA conversion circuit;The differential input charge-voltage conversion circuit, band-pass filter circuit, integration circuit, effective value conversion circuit and 4-20mA conversion circuit are sequentially connected;The power supply is connected respectively with the differential input charge-voltage conversion circuit, band-pass filter circuit, integration circuit, effective value conversion circuit and 4-20mA conversion circuit;The differential input charge-voltage conversion circuit is connected to the PE vibration sensor, and the 4-20mA conversion circuit is used to output 4-20mA vibration speed current signal, when there is larger impact signal component in sensor input, make output signal unsaturated, meet the detection of vibration signal component.

Description

Technical Field

[0001] This invention relates to a vibration signal conditioning circuit that resists shock saturation. Background Technology

[0002] Currently, vibration sensor solutions typically convert the vibration acceleration voltage signal from the IEPE interface into a velocity signal output by integrating it through an integrator.

[0003] In many applications of vibration sensors, the detected signals are not only vibration signals but also often accompanied by impact signals. Vibration sensors, such as piezoelectric vibration sensors with IEPE interfaces, are usually more sensitive in the impact signal frequency band. The impact component of the signal can easily saturate the output, which is not conducive to the detection of vibration component signals. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a vibration signal conditioning circuit that resists impact saturation, so that the output signal is not saturated when the sensor input has a large impact signal component, thereby satisfying the detection of vibration signal components.

[0005] In a first aspect, the present invention provides a vibration signal conditioning circuit that resists shock saturation for connection with a PE vibration sensor, comprising: a differential input charge-to-voltage circuit, a bandpass filter circuit, an integral circuit, an RMS conversion circuit, a power supply, and a 4-20mA conversion circuit;

[0006] The differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit are connected in sequence; the power supply is connected to the differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit respectively.

[0007] The differential input charge-to-voltage circuit is connected to the PE vibration sensor, and the 4-20mA conversion circuit is used to output a 4-20mA vibration velocity current signal.

[0008] Furthermore, the differential input charge-to-voltage circuit includes: electrostatic diode D1, electrostatic diode D2, resistor R1, resistor R2, resistor R3, resistor R4, integrating capacitor CF1, integrating capacitor CF2, and the negative input terminal of operational amplifier U1B.

[0009] One end of resistor R1 and one end of resistor R2 are both connected to the PE vibration sensor, and one end of resistor R1 and one end of resistor R2 are connected in parallel with electrostatic diode D1; the other end of resistor R1 is connected to one end of integrating capacitor CF1, one end of resistor R3 and pin 6 of operational amplifier U1B; the other end of resistor R2 is connected to pin 5 of operational amplifier U1B, one end of resistor R4 and one end of integrating capacitor CF2, pins 4 and 8 of operational amplifier U1B are respectively connected to the power supply, and one end of electrostatic diode D2, pin 7 of operational amplifier U1B, the other end of resistor R3 and the other end of integrating capacitor CF1 are all connected to the bandpass filter circuit;

[0010] The other end of the electrostatic diode D2, the other end of the resistor R4, and the other end of the integrating capacitor CF2 are all grounded.

[0011] Furthermore, the integrating circuit includes resistors R56, R57, 70, R55, R59, R60, R58, 71, operational amplifier U10A, operational amplifier U10B, capacitor C57, and capacitor C60.

[0012] One end of resistor R57 is connected to the bandpass filter circuit, and the other end of resistor R57 is connected to pin 2 of operational amplifier U10A and one end of resistor R70. One end of resistor R56 is grounded, and the other end of resistor R56 is connected to pin 3 of operational amplifier U10A. Pins 4 and 8 of operational amplifier U10A are connected to the power supply. The other end of resistor R70 and pin 1 of operational amplifier U10A are connected to one end of resistor R59, and the other end of resistor R59 is connected to resistor R60 through capacitor C57. One end of the resistor R60 is connected to pin 6 of the operational amplifier U10B, one end of the capacitor C60, and one end of the resistor R71. One end of the resistor R55 is grounded, and the other end of the resistor R55 is connected to pin 5 of the operational amplifier U10B. Pins 4 and 8 of the operational amplifier U10B are connected to the power supply. Pin 7 of the operational amplifier U10B, the other end of the capacitor C60, and the other end of the resistor R71 are all connected to one end of the resistor R58. The other end of the resistor R58 is connected to the RMS conversion circuit.

[0013] Furthermore, the 4-20mA conversion circuit includes: resistors R80, R76, R77, R84, R89, electrostatic diodes D16 and D18, operational amplifier U12A, MOSFET Q1, MOSFET Q2, and an output interface.

[0014] One end of resistor R80 is connected to the RMS conversion circuit, and the other end of resistor R80 is connected to pin 3 of operational amplifier U12A. Pins 4 and 8 of operational amplifier U12A are connected to the power supply. One end of resistor R84 is connected to pin 2 of operational amplifier U12A and the source (S) terminal of MOSFET Q1, respectively. The other end of resistor R84 is grounded through resistor R89. Pin 1 of operational amplifier U12A is connected to the gate (G) terminal of MOSFET Q1. The power supply is connected to one end of resistor R76, one end of electrostatic diode D16, and resistor R77. At one end, the drain of the MOSFET Q1 is connected to the other end of the resistor R76, the other end of the electrostatic diode D16, and pin 5 of the operational amplifier U12B. The other end of the resistor R77 is connected to pin 6 of the operational amplifier U12B and the source of the MOSFET Q2. Pins 4 and 8 of the operational amplifier U12B are connected to the power supply. Pin 7 of the operational amplifier U12B is connected to the gate of the MOSFET Q2. The drain of the MOSFET Q2 is connected to one end of the electrostatic diode D18 and the output interface. The other end of the electrostatic diode D18 is grounded.

[0015] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0016] The vibration signal conditioning circuit provided in this application embodiment is designed to resist shock saturation. The PE interface input, combined with a charge-to-voltage circuit with relatively low gain, can meet the requirement that the vibration acceleration voltage signal output of the sensor is not saturated under relatively large impacts.

[0017] A bandpass filter circuit is added to the front end to prevent signals in the impulse frequency band from entering the integrator, thus ensuring the dynamic range of the integrator's output signal.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This is a block diagram of the vibration signal conditioning circuit of the present invention;

[0021] Figure 2 This is a schematic diagram of the differential input charge-to-voltage signal of the present invention;

[0022] Figure 3 This is a schematic diagram of the bandpass filter circuit of the present invention;

[0023] Figure 4 This is a schematic diagram of the integrator circuit of the present invention;

[0024] Figure 5 This is a schematic diagram of the RMS conversion circuit of the present invention;

[0025] Figure 6 This is a schematic diagram of the 4-20mA conversion circuit of the present invention. Detailed Implementation

[0026] The overall concept of the technical solution in this application embodiment is as follows:

[0027] The differential input charge-to-voltage circuit converts the vibration acceleration charge signal input from the PE interface into a vibration acceleration voltage signal. Because the gain of the charge-to-voltage circuit is designed to be relatively small, it ensures that the output of the charge-to-voltage circuit will not saturate when the signal from the impact frequency band comes in.

[0028] The vibration acceleration voltage signal is filtered by a bandpass filter to remove signals in the impact frequency band before being output to the integrator circuit. This ensures that when there is a large impact signal at the input, the impact signal will not be carried over to the integrator. The filtered vibration acceleration voltage signal is then integrated by the integrator to convert it into a vibration velocity voltage signal. Next, the vibration velocity voltage signal passes through an RMS converter circuit to transform it into a DC voltage signal representing the velocity magnitude. Finally, it passes through a 4-20mA conversion circuit to convert the vibration velocity signal into a 4-20mA current output.

[0029] A reasonable front-end gain allocation scheme and a subsequent bandpass filter circuit ensure that the output is not easily saturated when the sensor is subjected to impact. At the same time, the output signal is output through a 4-20mA interface, making the output less susceptible to interference signals from the common ground loop.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a vibration signal conditioning circuit that resists shock saturation for connection with a PE vibration sensor, including: a differential input charge-to-voltage circuit, a bandpass filter circuit, an integral circuit, an RMS conversion circuit, a power supply, and a 4-20mA conversion circuit;

[0032] The differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit are connected in sequence; the power supply is connected to the differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit respectively.

[0033] The differential input charge-to-voltage circuit is connected to the PE vibration sensor, and the 4-20mA conversion circuit is used to output a 4-20mA vibration velocity current signal.

[0034] like Figure 2 As shown, the differential input charge-to-voltage circuit includes: an electrostatic diode D1, an electrostatic diode D2, resistors R1, R2, R3, and R4, integrating capacitors CF1 and CF2, and the negative input terminal of operational amplifier U1B. One end of resistor R1 and one end of resistor R2 are both connected to the PE vibration sensor, and one end of resistor R1 and one end of resistor R2 are connected in parallel with the electrostatic diode D1. The other end of resistor R1 is connected to one end of integrating capacitor CF1, one end of resistor R3, and pin 6 of operational amplifier U1B. The other end of resistor R2 is connected to pin 5 of operational amplifier U1B, one end of resistor R4, and one end of integrating capacitor CF2. Pins 4 and 8 of operational amplifier U1B are respectively connected to... The power supply is connected to the bandpass filter circuit via one end of the electrostatic diode D2, pin 7 of the operational amplifier U1B, the other end of the resistor R3, and the other end of the integrating capacitor CF1. The other ends of the electrostatic diode D2, the other ends of the resistor R4, and the other ends of the integrating capacitor CF2 are grounded. The differential input charge-to-voltage circuit will not saturate its output under a charge input of 30000pC. The power supply is connected to J2, and is connected to one end of capacitor C25, one end of capacitor C26, and V- via pin 1 of J2. Pin 2 of J2 is connected to one end of capacitor C36, one end of capacitor C37, and V+. The other ends of capacitors C25, C26, C36, and C37 are all grounded.

[0035] like Figure 2 The diagram shows a differential input charge-to-voltage circuit, mainly composed of three parts: input / output protection, integrating capacitors, and an amplifier. D1 and D2 are the input and output protection capacitors, respectively, and CF1 and CF2 are the integrating capacitors. According to:

[0036] U=Q / CF=Q / ((CF1*CF2) / (CF1+CF2));

[0037] The amplification function of the amplifier enables the conversion of charge to voltage.

[0038] like Figure 3 As shown, this is a bandpass filter circuit, which mainly consists of resistors, capacitors, and operational amplifiers.

[0039] like Figure 4As shown, the integrating circuit includes resistors R56, R57, R70, R55, R59, R60, R58, and R71, operational amplifier U10A, operational amplifier U10B, capacitor C57, and capacitor C60. One end of resistor R57 is connected to the bandpass filter circuit, and the other end of resistor R57 is connected to pin 2 of operational amplifier U10A and one end of resistor R70. One end of resistor R56 is grounded, and the other end of resistor R56 is connected to pin 3 of operational amplifier U10A. Pins 4 and 8 of operational amplifier U10A are connected to the power supply. The other end of resistor R70 and pin 1 of operational amplifier U10A are connected to... One end of resistor R59 is connected to the other end of resistor R60 via capacitor C57. The other end of resistor R60 is connected to pin 6 of operational amplifier U10B, one end of capacitor C60, and one end of resistor R71. One end of resistor R55 is grounded, and the other end of resistor R55 is connected to pin 5 of operational amplifier U10B. Pins 4 and 8 of operational amplifier U10B are connected to the power supply. Pin 7 of operational amplifier U10B, the other end of capacitor C60, and the other end of resistor R71 are all connected to one end of resistor R58. The other end of resistor R58 is connected to the RMS conversion circuit.

[0040] like Figure 4 As shown, this is an integrating circuit, which uses operational amplifiers and capacitor feedback to form the integrating circuit.

[0041] like Figure 5 As shown, the RMS conversion circuit is implemented using a dedicated chip. In this case, the AD536A from ADI is used to convert the AC voltage signal into an RMS output.

[0042] like Figure 6As shown, the 4-20mA conversion circuit includes: resistors R80, R76, R77, R84, R89, ESD diodes D16 and D18, operational amplifier U12A, MOSFET Q1, MOSFET Q2, and an output interface. One end of resistor R80 is connected to the RMS conversion circuit, and the other end of resistor R80 is connected to pin 3 of operational amplifier U12A. Pins 4 and 8 of operational amplifier U12A are connected to the power supply. One end of resistor R84 is connected to pin 2 of operational amplifier U12A and the source (S) terminal of MOSFET Q1, and the other end of resistor R84 is grounded through resistor R89. Pin 1 of operational amplifier U12A is connected to the power supply. The gate (G) of MOSFET Q1 is connected to the power supply, which is connected to one end of resistor R76, one end of electrostatic diode D16, and one end of resistor R77. The drain (D) of MOSFET Q1 is connected to the other end of resistor R76, the other end of electrostatic diode D16, and pin 5 of operational amplifier U12B. The other end of resistor R77 is connected to pin 6 of operational amplifier U12B and the source (S) of MOSFET Q2. Pins 4 and 8 of operational amplifier U12B are connected to the power supply. Pin 7 of operational amplifier U12B is connected to the gate (G) of MOSFET Q2. The drain (D) of MOSFET Q2 is connected to one end of electrostatic diode D18 and the output interface. The other end of electrostatic diode D18 is grounded.

[0043] Part 5: 4-20mA Conversion Circuit

[0044] like Figure 6 As shown, the 4-20mA conversion circuit converts the true RMS speed DC voltage signal into a 4-20mA current signal, which is then output.

[0045] This invention uses discrete components to construct a 4-20mA conversion circuit, which makes the circuit more reliable and flexible to adjust.

[0046] The input voltage is input through R80. Assuming the input voltage is Uin, since op-amp U12A is in normal amplification mode, and due to the virtual short characteristic of the op-amp input, the voltage at pin 2 of op-amp U12A is also Uin. Therefore, the current flowing through R84 and R89 is:

[0047] Ir = Uin / (R84+R89);

[0048] Due to the characteristics of the MOSFET, there is no current at the gate (g) of Q1, and there is also no current at pin 5 of op-amp U12A. When the voltage across R76 has not yet reached the turn-on voltage of ESD D16, the current flowing through R76 is equal to the current flowing through R84 and R89. Therefore, the voltage across R76 is:

[0049] Ur76=Ir*R76=Uin / (R84+R89)*R76;

[0050] Since op-amp U12B is also in normal amplification mode, the voltages at pins 5 and 6 are equal. Therefore, the voltage across R77 should be equal to the voltage across R76.

[0051] Ur77=Ur76=Uin / (R84+R89)*R76;

[0052] The current flowing through R77 is:

[0053] Ir77=Uin / (R84+R99)*R76 / R77;

[0054] Due to the characteristics of the MOSFET, there is no current at the gate (g) terminal of Q2, and there is also no current at pin 6 of the op-amp input. Therefore, all the current flowing through R77 is output to the load through the MOSFET Q2. The output current is:

[0055] Iout=Ir77=Uin / (R84+R89)*R76 / R77;

[0056] At the same time, ESD D16 also limits the maximum output current of the circuit. When the input signal is relatively large, when the voltage Ur76 across R76 reaches the clamping voltage of ESD D16, the voltage Ur76 across R76 no longer increases linearly with the increase of the input. Therefore, the maximum output current of the constant current source will be limited by the clamping voltage of ESD D16.

[0057] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A vibration signal conditioning circuit resistant to shock saturation, used for connection with a PE vibration sensor, characterized in that, include: Differential input charge-to-voltage circuit, bandpass filter circuit, integrator circuit, RMS conversion circuit, power supply, and 4-20mA conversion circuit; The differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit are connected in sequence; the power supply is connected to the differential input charge-to-voltage circuit, bandpass filter circuit, integral circuit, RMS conversion circuit, and 4-20mA conversion circuit respectively. The differential input charge-to-voltage circuit is connected to the PE vibration sensor, and the 4-20mA conversion circuit is used to output a 4-20mA vibration velocity current signal. The 4-20mA conversion circuit includes: resistors R80, R76, R77, R84, R89, electrostatic diodes D16 and D18, operational amplifier U12A, MOSFET Q1 and Q2, and an output interface. One end of resistor R80 is connected to the RMS conversion circuit, and the other end of resistor R80 is connected to pin 3 of operational amplifier U12A. Pins 4 and 8 of operational amplifier U12A are connected to the power supply. One end of resistor R84 is connected to pin 2 of operational amplifier U12A and the source (S) terminal of MOSFET Q1, respectively. The other end of resistor R84 is grounded through resistor R89. Pin 1 of operational amplifier U12A is connected to the gate (G) terminal of MOSFET Q1. The power supply is connected to one end of resistor R76, one end of electrostatic diode D16, and resistor R77. One end of the MOSFET Q1 is connected to the other end of the resistor R76, the other end of the electrostatic diode D16, and pin 5 of the operational amplifier U12B. The other end of the resistor R77 is connected to pin 6 of the operational amplifier U12B and the source of the MOSFET Q2. Pins 4 and 8 of the operational amplifier U12B are connected to the power supply. Pin 7 of the operational amplifier U12B is connected to the gate of the MOSFET Q2. The drain of the MOSFET Q2 is connected to one end of the electrostatic diode D18 and the output interface. The other end of the electrostatic diode D18 is grounded. The differential input charge-to-voltage circuit includes: electrostatic diode D1, electrostatic diode D2, resistor R1, resistor R2, resistor R3, resistor R4, integrating capacitor CF1, integrating capacitor CF2, and the negative input terminal of operational amplifier U1B. One end of resistor R1 and one end of resistor R2 are both connected to the PE vibration sensor, and one end of resistor R1 and one end of resistor R2 are connected in parallel with electrostatic diode D1; the other end of resistor R1 is connected to one end of integrating capacitor CF1, one end of resistor R3 and pin 6 of operational amplifier U1B; the other end of resistor R2 is connected to pin 5 of operational amplifier U1B, one end of resistor R4 and one end of integrating capacitor CF2, pins 4 and 8 of operational amplifier U1B are respectively connected to the power supply, and one end of electrostatic diode D2, pin 7 of operational amplifier U1B, the other end of resistor R3 and the other end of integrating capacitor CF1 are all connected to the bandpass filter circuit; The other end of the electrostatic diode D2, the other end of the resistor R4, and the other end of the integrating capacitor CF2 are all grounded.

2. The vibration signal conditioning circuit against shock saturation according to claim 1, characterized in that, The integrating circuit includes: resistors R56, R57, 70, R55, R59, R60, R58, and 71; operational amplifier U10A; operational amplifier U10B; capacitor C57; and capacitor C60. One end of resistor R57 is connected to the bandpass filter circuit, and the other end of resistor R57 is connected to pin 2 of operational amplifier U10A and one end of resistor R70. One end of resistor R56 is grounded, and the other end of resistor R56 is connected to pin 3 of operational amplifier U10A. Pins 4 and 8 of operational amplifier U10A are connected to the power supply. The other end of resistor R70 and pin 1 of operational amplifier U10A are connected to one end of resistor R59, and the other end of resistor R59 is connected to resistor R60 through capacitor C57. One end of the resistor R60 is connected to pin 6 of the operational amplifier U10B, one end of the capacitor C60, and one end of the resistor R71. One end of the resistor R55 is grounded, and the other end of the resistor R55 is connected to pin 5 of the operational amplifier U10B. Pins 4 and 8 of the operational amplifier U10B are connected to the power supply. Pin 7 of the operational amplifier U10B, the other end of the capacitor C60, and the other end of the resistor R71 are all connected to one end of the resistor R58. The other end of the resistor R58 is connected to the RMS conversion circuit.

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