阅读说明：本技术 一种数字低频地震传感器 (Digital low-frequency seismic sensor ) 是由 张晓鹏 王同东 王敏超 李欣 崔甲甲 朱维 肖卫国 于 2019-12-09 设计创作，主要内容包括：本发明提供了一种数字低频地震传感器,解决现有地震探测系统无法直接输出数字信号,或存在造价高、结构复杂、功耗较大,以及无法探测地壳深部低频地震信号的问题。该传感器包括摆体系统、电磁换能器、检测级电路、多级积分器、量化器、驱动级电路、PID控制器、DAC；摆体系统感应到振动产生振动信号,经电磁换能器转换为电压信号；电压信号经检测级电路反向放大,进入多级积分器经采样保持和积分滤波；经滤波后的电压信号由量化器进行模数转换；DAC用于将量化器输出的数字位流生成脉冲宽度调制电压,经PID控制器调理为控制电压,由驱动级电路转化为电磁换能器的线圈电流,线圈电流经磁场换能器转换为电磁力,用于平衡摆体系统的运动趋势。(The invention provides a digital low-frequency seismic sensor, which solves the problems that the existing seismic detection system cannot directly output digital signals, or has high manufacturing cost, complex structure, large power consumption and cannot detect low-frequency seismic signals in the deep part of the earth crust. The sensor comprises a pendulum system, an electromagnetic transducer, a detection stage circuit, a multi-stage integrator, a quantizer, a driving stage circuit, a PID controller and a DAC; the pendulum system induces vibration to generate a vibration signal, and the vibration signal is converted into a voltage signal through the electromagnetic transducer; the voltage signal is reversely amplified by a detection stage circuit, enters a multi-stage integrator and is subjected to sampling holding and integral filtering; performing analog-to-digital conversion on the filtered voltage signal by a quantizer; the DAC is used for generating pulse width modulation voltage from the digital bit stream output by the quantizer, the pulse width modulation voltage is conditioned into control voltage through the PID controller, the control voltage is converted into coil current of the electromagnetic transducer through the driving stage circuit, and the coil current is converted into electromagnetic force through the magnetic field transducer and used for balancing the motion trend of the pendulum body system.)

1. A digital low frequency seismic sensor, comprising: the digital feedback control device comprises a signal pickup unit and a digital feedback control unit;

the signal pickup unit comprises a pendulum system, an electromagnetic transducer (1), a detection stage circuit, a multi-stage integrator and a quantizer (9);

the pendulum body system induces vibration to generate a vibration signal, and the vibration signal is converted into a voltage signal through the electromagnetic transducer (1); the voltage signal is reversely amplified by a detection stage circuit, enters a multi-stage integrator and is subjected to sampling holding and integral filtering; the analog-to-digital conversion is carried out on the filtered voltage signal by a quantizer (9), and if the voltage signal is greater than a threshold value, the quantizer (9) outputs a digital high level + 1; if the voltage signal is less than or equal to the threshold value, the quantizer (9) outputs a digital low level-1;

the digital feedback control unit comprises a driving stage circuit, a PID controller (2) and a DAC;

the DAC is connected with the output of the quantizer (9) and is used for generating pulse width modulation voltage from the digital bit stream output by the quantizer (9); the pulse width modulation voltage is conditioned into control voltage through the PID controller (2), and is converted into coil current of the electromagnetic transducer (1) through the driving stage circuit, and the coil current is converted into electromagnetic force through the magnetic field transducer and is used for balancing the motion trend of the pendulum system.

2. The digital low frequency seismic sensor of claim 1, wherein: the electromagnetic transducer (1) comprises an induced voltage Vcoil and a coil resistor Rcoil, wherein one end of the induced voltage Vcoil is connected with one end of the coil resistor Rcoil;

the detection stage circuit comprises a detection stage operational amplifier (3) and a feedback resistor R1;

the other end of the induced voltage Vcoil is connected to a negative input end (31) of the detection-stage operational amplifier through an input resistor R2, two ends of a feedback resistor R1 are respectively connected with the negative input end (31) of the detection-stage operational amplifier and an output end (33) of the detection-stage operational amplifier, a positive input end (32) of the detection-stage operational amplifier is connected with the other end of a coil resistor Rcoil, the other end of the coil resistor Rcoil is connected with one end of a matching resistor R3, and the other end of the matching resistor R3 is grounded.

3. The digital low frequency seismic sensor of claim 2, wherein: the matching resistor R3 is equal to the coil resistor Rcoil, and the feedback resistor R1 is equal to the input resistor R2.

4. The digital low frequency seismic sensor of claim 3, wherein: the multistage integrator adopts a 3-order distributed feedback structure or a 2-order distributed feedback structure.

5. The digital low frequency seismic sensor according to claim 4, wherein: the 3-order distributed feedback structure comprises a first-stage filter (6), a second-stage filter (7) and a third-stage filter (8);

the first-stage filter (6) comprises a first subtracter (61), a feedforward amplifier K1 and a first integrator (62), the second-stage filter (7) comprises a second subtracter (71), a feedforward amplifier K2 and a second integrator (72), and the third-stage filter (8) comprises a third subtracter (81), a feedforward amplifier K3 and a third integrator (82);

the detection device comprises a first subtracter (61), a feedforward amplifier K1, a first integrator (62), a second subtracter (71), a feedforward amplifier K2, a second integrator (72), a third subtracter (81), a feedforward amplifier K3 and a third integrator (82) which are sequentially connected, wherein the positive input end of the first subtracter (61) is connected to the output end (33) of the detection-stage operational amplifier, the output end of the third integrator (82) is connected with the input end of the quantizer (9), and the negative input end of the first subtracter (61), the negative input end of the second subtracter (71) and the negative input end of the third subtracter (81) are respectively connected with the output end of the quantizer (9).

6. The digital low frequency seismic sensor according to claim 4, wherein: the 2 nd order distributed feedback structure comprises a first stage filter (6) and a second stage filter (7);

the first-stage filter (6) comprises a first subtracter (61), a feedforward amplifier K1 and a first integrator (62), and the second-stage filter (7) comprises a second subtracter (71), a feedforward amplifier K2 and a second integrator (72);

the first subtractor (61), the feedforward amplifier K1, the first integrator (62), the second subtractor (71), the feedforward amplifier K2 and the second integrator (72) are sequentially connected, the positive input end of the first subtractor (61) is connected to the output end (33) of the detection-stage operational amplifier, the output end of the second integrator (72) is connected with the input end of the quantizer (9), and the negative input end of the first subtractor (61) and the negative input end of the second subtractor (71) are respectively connected with the output end of the quantizer (9).

7. The digital low frequency seismic sensor according to claim 5 or 6, wherein: the DAC comprises an analog switch (10), and the input end of the analog switch (10) is connected with the output end of the quantizer (9);

when the input digital signal is +1, the analog switch (10) connected with the positive control voltage + Vfb is conducted; when the input digital signal is-1, the analog switch (10) connected with the negative control voltage-Vfb is conducted.

8. The digital low frequency seismic sensor of claim 7, wherein: the PID controller (2) comprises an addition circuit (21) and three amplification branches (22) connected in parallel, wherein the three amplification branches (22) are respectively a proportional amplifier, an integral amplifier and a differential amplifier;

one ends of the proportional amplifier, the integral amplifier and the differential amplifier are all connected with the output end of the analog switch (10), and the other ends of the proportional amplifier, the integral amplifier and the differential amplifier are all connected with three positive input ends of the addition circuit (21).

9. The digital low frequency seismic sensor of claim 8, wherein: the driving stage circuit comprises a control stage operational amplifier (4);

the positive input end (42) of the control-stage operational amplifier is connected with the output end of the addition circuit (21), the negative input end (41) of the control-stage operational amplifier is connected with the other end of the coil resistor Rcoil, and the output end (43) of the control-stage operational amplifier is connected with the other end of the induced voltage Vcoil.

10. The digital low frequency seismic sensor of claim 1, wherein: the quantizer is a 1-bit quantizer or a low-bit quantizer;

the DAC and the quantizer correspond to a 1-bit DAC or a low-bit DAC.

Technical Field

The invention relates to the field of sensors, in particular to a digital low-frequency seismic sensor.

Background

The existing exploration seismic detection system mainly comprises a geophone and a data acquisition unit, and is structurally characterized in that the geophone is used as a sensing unit to pick up seismic signals and output analog voltage, and the data acquisition unit converts the voltage signals into digital quantity. The detection system can not directly output digital signals, and the digital acquisition of the detection system depends on an analog-digital conversion chip, so that the detection system has the problems of high manufacturing cost, complex structure, large power consumption and the like; in addition, the conventional moving-coil geophone adopts a speed type electromagnetic transduction principle, is of a non-feedback open-loop structure, limits the lower cut-off frequency to be 4 Hz-50 Hz, cannot detect low-frequency seismic signals reflected and transmitted from the deep part of the earth crust, and influences the detection precision and depth of underground medium structures and oil and gas resources.

Disclosure of Invention

The invention provides a digital low-frequency seismic sensor, aiming at solving the technical problems that the existing seismic detection system can not directly output digital signals, or an analog-digital conversion chip has high manufacturing cost, complex structure and large power consumption, and can not detect low-frequency seismic signals reflected and transmitted in the deep part of the crust, thereby influencing the detection precision and depth of underground medium structures and oil-gas resources.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a digital low-frequency seismic sensor is characterized in that: the digital feedback control device comprises a signal pickup unit and a digital feedback control unit; the signal pickup unit comprises a pendulum system, an electromagnetic transducer, a detection stage circuit, a multi-stage integrator and a quantizer;

the pendulum body system induces vibration to generate a vibration signal, and the vibration signal is converted into a voltage signal through the electromagnetic transducer; the voltage signal is reversely amplified by a detection stage circuit, enters a multi-stage integrator and is subjected to sampling holding and integral filtering; the analog-to-digital conversion is carried out on the filtered voltage signal by a quantizer, and if the voltage signal is greater than a threshold value, the quantizer outputs a digital high level + 1; if the voltage signal is less than or equal to the threshold value, the quantizer outputs a digital low level-1;

the digital feedback control unit comprises a driving stage circuit, a PID controller and a DAC.

The DAC is connected with the output of the quantizer and used for generating pulse width modulation voltage from the digital bit stream output by the quantizer; the pulse width modulation voltage is conditioned into control voltage through a PID controller, the control voltage is converted into coil current of an electromagnetic transducer through a driving stage circuit, and the coil current is converted into electromagnetic force through a magnetic field transducer and is used for balancing the movement trend of the pendulum body system.

Further, the electromagnetic transducer comprises an induced voltage Vcoil and a coil resistance Rcoil, wherein one end of the induced voltage Vcoil is connected with one end of the coil resistance Rcoil;

the detection stage circuit comprises a detection stage operational amplifier and a feedback resistor R1;

the other end of the induced voltage Vcoil is connected to the negative input end of the detection-stage operational amplifier through an input resistor R2, two ends of a feedback resistor R1 are respectively connected to the negative input end of the detection-stage operational amplifier and the output end of the detection-stage operational amplifier, the positive input end of the detection-stage operational amplifier is connected to the other end of a coil resistor Rcoil, the other end of the coil resistor Rcoil is connected to one end of a matching resistor R3, and the other end of the matching resistor R3 is grounded.

Further, the matching resistor R3 is equal to the coil resistor Rcoil, and the feedback resistor R1 is equal to the input resistor R2.

Further, the multistage integrator adopts a 3-order distributed feedback structure or a 2-order distributed feedback structure.

Further, the 3 rd order distributed feedback structure comprises a first-stage filter, a second-stage filter and a third-stage filter;

the first-stage filter comprises a first subtracter, a feedforward amplifier K1 and a first integrator, the second-stage filter comprises a second subtracter, a feedforward amplifier K2 and a second integrator, and the third-stage filter comprises a third subtracter, a feedforward amplifier K3 and a third integrator;

the first subtractor, the feedforward amplifier K1, the first integrator, the second subtractor, the feedforward amplifier K2, the second integrator, the third subtractor, the feedforward amplifier K3 and the third integrator are sequentially connected, the positive input end of the first subtractor is connected with the output end of the detection-stage operational amplifier, the output end of the third integrator is connected with the input end of the quantizer, and the negative input end of the first subtractor, the negative input end of the second subtractor and the negative input end of the third subtractor are respectively connected with the output end of the quantizer.

Further, the 2 nd order distributed feedback structure comprises a first stage filter and a second stage filter;

the first-stage filter comprises a first subtracter, a feedforward amplifier K1 and a first integrator, and the second-stage filter comprises a second subtracter, a feedforward amplifier K2 and a second integrator;

the first subtractor, the feedforward amplifier K1, the first integrator, the second subtractor, the feedforward amplifier K2 and the second integrator are sequentially connected, the positive input end of the first subtractor is connected with the output end of the detection-stage operational amplifier, the output end of the second integrator is connected with the input end of the quantizer, and the negative input end of the first subtractor and the negative input end of the second subtractor are respectively connected with the output end of the quantizer.

Further, the DAC comprises an analog switch, and the input end of the analog switch is connected with the output end of the quantizer;

when the input digital signal is +1, the analog switch connected with the positive control voltage + Vfb is conducted; when the input digital signal is-1, the analog switch connected with the negative control voltage-Vfb is conducted.

Furthermore, the PID controller comprises an addition circuit and three amplification branches connected in parallel, wherein the three amplification branches are respectively a proportional amplifier, an integral amplifier and a differential amplifier;

one ends of the proportional amplifier, the integral amplifier and the differential amplifier are all connected with the output end of the analog switch, and the other ends of the proportional amplifier, the integral amplifier and the differential amplifier are all connected with three positive input ends of the addition circuit.

Further, the driving stage circuit comprises a control stage operational amplifier;

the positive input end of the control-stage operational amplifier is connected with the output end of the addition circuit, the negative input end of the control-stage operational amplifier is connected with the other end of the coil resistor Rcoil, and the output end of the control-stage operational amplifier is connected with the other end of the induced voltage Vcoil.

Further, the quantizer is a 1-bit quantizer or a lower-bit quantizer; the DAC and the quantizer correspond to a 1-bit DAC or a low-bit DAC.

Compared with the prior art, the invention has the advantages that:

1. the digital low-frequency seismic sensor has the advantages that digital signals are directly output, an analog-digital mixed circuit system is adopted for sampling and quantifying, an analog-digital conversion chip is not needed, and the digital low-frequency seismic sensor has the characteristics of good low-frequency response, compact structure, low power consumption, large dynamic range and good linearity;

the pendulum body system and the electromagnetic transducer are connected into the detection stage circuit and the driving stage circuit, so that the pendulum body can realize the detection of the movement of the pendulum body by relying on the original coil, the ground movement speed is converted into induced electromotive force, the feedback electromagnetic force is applied, the movement trend of the pendulum body is balanced, the low-frequency bandwidth of the mechanical system is expanded, and the closed-loop feedback is realized.

2. The digital low-frequency seismic sensor has good low-frequency response, and the low-frequency band of the pendulum system is expanded by adopting a force balance technology;

3. the digital low-frequency seismic sensor has strong compatibility, and a circuit system can be directly connected to the existing moving-coil geophone or a similar pendulum body and energy conversion system, so that the low-frequency response is expanded, and a digital signal is output.

4. The multi-stage integrator in the sensor can adopt a 3-order distributed feedback structure, and the 3-order structure has the advantages of high-order noise shaping characteristic and small quantization noise;

the multistage integrator can also adopt a 2-order distributed feedback structure, a third pole filter in the 3-order distributed feedback structure is omitted by the structure, the structure is simpler, the power consumption is lower, and the system is easy to stabilize.

Drawings

FIG. 1 is a schematic diagram of a digital low frequency seismic sensor of the present invention;

FIG. 2 is a schematic circuit diagram of the detection stage circuit, the driving stage circuit and the PID controller of the digital low frequency seismic sensor of the invention;

FIG. 3 is a schematic circuit diagram of a multi-stage integrator, quantizer and DAC of a first embodiment of a digital low frequency seismic sensor of the present invention;

FIG. 4 is a schematic circuit diagram of a multi-stage integrator, quantizer and DAC of a second embodiment of the digital low frequency seismic sensor of the present invention;

wherein the reference numbers are as follows:

1-an electromagnetic transducer, 2-a PID controller, 21-an adder circuit, 22-an amplification branch, 3-an operational amplifier, 31-a negative input terminal of a detection-stage operational amplifier, 32-a positive input terminal of a detection-stage operational amplifier, 33-an output terminal of a detection-stage operational amplifier, 4-a control-stage operational amplifier, 41-a negative input terminal of a control-stage operational amplifier, 42-a positive input terminal of a control-stage operational amplifier, 43-an output terminal of a control-stage operational amplifier, 5-a circuit reference point, 6-a first-stage filter, 61-a first subtractor, 62-a first integrator, 7-a second-stage filter, 71-a second subtractor, 72-a second integrator, 8-a third-stage filter, 81-a third subtractor, 82-third integrator, 9-quantizer, 10-analog switch.

Detailed Description

The invention is described in further detail below with reference to the figures and specific embodiments.