阅读说明：本技术 一种基于pid算法的瞬变电磁发射系统及其控制方法 (Transient electromagnetic transmitting system based on PID algorithm and control method thereof ) 是由 姜元 姜润强 张振东 刘阳 于 2020-10-30 设计创作，主要内容包括：一种基于PID算法的瞬变电磁发射系统及其控制方法,解决了现有瞬变电磁发射装置不足的问题。该系统包括：主控电路、光耦开关、H桥路、霍尔传感器、模数转换器和负载线圈；主控电路发出弱电信号,通过光耦开关将弱电信号转换为强电信号,并驱动H桥路开启和闭合,在负载线圈中形成电流信号,传输回H桥路,形成闭环；霍尔传感器采集流经负载线圈上的模拟信号,由模数转换器进行转换,将数字信号反馈至主控电路。本发明突破了传统瞬变电磁发射电流关断时间受负载线圈特性的限制,延长了发射电流关断时间,发射电流的上升沿和下降沿的斜率固定,且线性度更高,能够更准确的剔除一次场对瞬变电磁信号的影响,得到更加准确的地下介质反演结果。(A transient electromagnetic transmitting system based on a PID algorithm and a control method thereof solve the problem of the deficiency of the existing transient electromagnetic transmitting device. The system comprises: the device comprises a main control circuit, an optical coupler switch, an H bridge circuit, a Hall sensor, an analog-to-digital converter and a load coil; the main control circuit sends out weak current signals, the weak current signals are converted into strong current signals through the optocoupler switch, the H bridge circuit is driven to be opened and closed, current signals are formed in the load coil and are transmitted back to the H bridge circuit, and a closed loop is formed; the Hall sensor collects analog signals flowing through the load coil, the analog signals are converted by the analog-to-digital converter, and the digital signals are fed back to the main control circuit. The method breaks through the limitation that the turn-off time of the traditional transient electromagnetic emission current is limited by the characteristics of the load coil, prolongs the turn-off time of the emission current, ensures the fixed slope of the rising edge and the falling edge of the emission current, has higher linearity, can more accurately eliminate the influence of a primary field on the transient electromagnetic signal, and obtains more accurate underground medium inversion results.)

1. A transient electromagnetic emission system based on a PID algorithm, the system comprising: the device comprises a main control circuit, an optical coupler switch, an H bridge circuit, a Hall sensor, an analog-to-digital converter and a load coil; the main control circuit sends out weak current signals, the weak current signals are converted into strong current signals through an optical coupler switch, the H bridge circuit is driven to be opened and closed, current signals are formed in the load coil and transmitted back to the H bridge circuit, and a closed loop is formed; the Hall sensor collects analog signals flowing through the load coil, the analog signals are converted by the analog-to-digital converter, and digital signals are fed back to the main control circuit.

2. The transient electromagnetic transmitting system based on the PID algorithm as claimed in claim 1, wherein the optocoupler switch is connected with the main control circuit and the control end of the H-bridge circuit, and two paths of the output end of the H-bridge circuit are respectively connected with the inlet and the outlet of the load coil to form a closed loop; the Hall sensor is sleeved on the load coil, and the analog-to-digital converter is connected with the main control circuit and the Hall sensor.

3. The transient electromagnetic emission system based on the PID algorithm as claimed in claim 1, wherein the optical coupling switch is a photocoupler to realize isolation of strong and weak current.

4. The transient electromagnetic transmission system based on PID algorithm as claimed in claim 1, wherein said H-bridge is composed of 4 MOS transistors.

5. A control method of a transient electromagnetic emission system based on PID algorithm according to any one of claims 1-4, characterized in that the method comprises the following steps:

the method comprises the following steps: initializing a main control circuit, and configuring an output current waveform curve comprising current magnitude, frequency, duty ratio and current turn-off time;

step two: the main control circuit transmits high-frequency PWM waves, the H bridge circuit switch is driven through the optocoupler switch, and current waveforms are obtained on the load coil;

step three: the Hall sensor is arranged on a load coil loop, collects the current waveform flowing through the load coil in real time, and simultaneously collects a feedback current value by using a high-speed analog-to-digital converter and feeds the feedback current value back to the main control circuit;

step four: the main control circuit compares the configured current value with the feedback current value, and utilizes a PID controller embedded in the main control circuit to regulate the duty ratio of the output PWM wave, so as to reduce the difference between the feedback current value flowing through the load coil and the configured value and obtain a current waveform matched with a configured curve on the load coil.

6. The control method of claim 5, wherein in step one, an emission period is divided into a plurality of discrete time points according to a configuration output waveform curve, a rising edge, a flat top section and a falling edge of the current curve are connected into a straight waveform related to the discrete time, the flat top section is a fixed current value, and the rising edge and the falling edge are current on and off time.

7. The control method according to claim 6, wherein the discrete point time interval of the rising edge and the flat top section is 100us, and the discrete point time interval of the falling edge is 5 us.

8. The control method according to claim 5, wherein in the first step, the current is selected to be a bipolar square wave with a duty cycle of 50% and a current of less than 50A, and the turn-off time is generally greater than 1 ms.

9. The control method according to claim 5, wherein the acquisition frequency of the high-speed analog-to-digital converter in step three is 1MSPS, and the high-speed analog-to-digital converter is in communication with the main control circuit through an SPI serial peripheral interface.

10. The control method of claim 5, wherein the discrete form of the PID controller in step four is:

u[n]＝k_pe[n]+k_i{e[n]+e[n-1]+e[n-2]+...}+k_d{e[n]-e[n-1]}

e[n]＝i_r(n)-i₀(n)

in the formula: i.e. i_r(n) represents a value of arrangement current, i₀(n) represents the sampled current value, e [ n ]]Representing the current deviation at that moment, u n]Represents the output PWM wave duty cycle; by pair k_p、k_i、k_dThe three parameters are adjusted to control the response characteristics of the transmitting system, and the current waveform matched with the configured curve is obtained.

Technical Field

The invention relates to the field of transient electromagnetic transmitting systems and control methods, in particular to a transient electromagnetic transmitting system based on a PID algorithm and a control method thereof.

Background

The transient electromagnetic method is used as a time domain geophysical prospecting method, a bipolar current square wave is introduced into a transmitting coil, and a receiving end sensor is used for receiving a primary field signal and a secondary field signal caused by induction of an underground medium. By analyzing the received signals, resistivity information of the subsurface medium is obtained.

The exploration of underground fossil energy and the exploitation of metal mineral reserves are the most main resource consumption, and the search of large-depth mineral reserves is an important way for relieving the energy crisis. Therefore, the invention of an efficient, accurate and deep resource detection instrument is an urgent problem at present.

The existing transmitting device and transmitting system for increasing the transient electromagnetic detection depth do not relate to the control of the turn-off time of the transmitting current. The turn-off time of the transient electromagnetic emission current directly influences the detection result, if the turn-off time is longer, the early signals received are fewer, the middle and late signals are more, and the deep geoelectrical information is reflected to be more. With the increase of the turn-off time, the deep information reflected by the resistivity curve is richer.

Disclosure of Invention

The invention aims to provide a transient electromagnetic transmitting system based on a PID algorithm and a control method thereof aiming at the defects of the conventional transient electromagnetic transmitting device.

A transient electromagnetic transmission system based on a PID algorithm, the system comprising: the device comprises a main control circuit, an optical coupler switch, an H bridge circuit, a Hall sensor, an analog-to-digital converter and a load coil; the main control circuit sends out weak current signals, the weak current signals are converted into strong current signals through an optical coupler switch, the H bridge circuit is driven to be opened and closed, current signals are formed in the load coil and transmitted back to the H bridge circuit, and a closed loop is formed; the Hall sensor collects analog signals flowing through the load coil, the analog signals are converted by the analog-to-digital converter, and digital signals are fed back to the main control circuit.

Preferably, the optocoupler switch is connected with a main control circuit and a control end of an H-bridge circuit, and two paths of output ends of the H-bridge circuit are respectively connected with an inlet and an outlet of the load coil to form a closed loop; the Hall sensor is sleeved on the load coil, and the analog-to-digital converter is connected with the main control circuit and the Hall sensor.

Preferably, the optical coupler switch is a photoelectric coupler, so that strong and weak current isolation is realized.

Preferably, the H-bridge is composed of 4 MOS transistors.

A method for controlling a transient electromagnetic emission system based on a PID algorithm, the method comprising the steps of:

the method comprises the following steps: initializing a main control circuit, and configuring an output current waveform curve comprising current magnitude, frequency, duty ratio and current turn-off time;

step two: the main control circuit transmits high-frequency PWM waves, the H bridge circuit switch is driven through the optocoupler switch, and current waveforms are obtained on the load coil;

step three: the Hall sensor is arranged on a load coil loop, collects the current waveform flowing through the load coil in real time, and simultaneously collects a feedback current value by using a high-speed analog-to-digital converter and feeds the feedback current value back to the main control circuit;

step four: the main control circuit compares the configured current value with the feedback current value, and utilizes a PID controller embedded in the main control circuit to regulate the duty ratio of the output PWM wave, so as to reduce the difference between the feedback current value flowing through the load coil and the configured value and obtain a current waveform matched with a configured curve on the load coil.

Preferably, in the first step, one emission cycle is divided into a plurality of discrete time points according to a configured output waveform curve, a rising edge, a flat top section and a falling edge of the current curve are connected into a linear waveform related to the discrete time, the flat top section is a fixed current value, and the rising edge and the falling edge are current on and off time.

Preferably, the discrete point time interval of the rising edge and the flat top segment is 100us, and the discrete point time interval of the falling edge is 5 us.

Preferably, in the first step, the current is selected to be less than 50A, the duty ratio is 50%, and the turn-off time is generally greater than 1 ms.

Preferably, the acquisition frequency of the high-speed analog-to-digital converter in the third step is 1MSPS, and the high-speed analog-to-digital converter is communicated with the main control circuit through the SPI serial peripheral interface.

Preferably, the discrete form of the PID controller in step four is:

u[n]＝k_pe[n]+k_i{e[n]+e[n-1]+e[n-2]+...}+k_d{e[n]-e[n-1]}

e[n]＝i_r(n)-i₀(n)

in the formula: i.e. i_r(n) represents a value of arrangement current, i₀(n) represents the sampled current value, e [ n ]]Representing the current deviation at that moment, u n]Represents the output PWM wave duty cycle; by pair k_p、k_i、k_dThe three parameters are adjusted to control the response characteristics of the transmitting system, and the current waveform matched with the configured curve is obtained.

Advantageous effects

Compared with the prior art, the invention breaks through the limitation that the turn-off time of the traditional transient electromagnetic emission current is limited by the characteristics of the load coil, greatly prolongs the turn-off time of the emission current, and is suitable for deep resource detection. The slopes of the rising edge and the falling edge of the emission current are fixed, the linearity is higher, the influence of a primary field on the transient electromagnetic signal can be eliminated more accurately, and a more accurate underground medium inversion result is obtained.

Drawings

FIG. 1: the invention relates to a transient electromagnetic transmitting system structure schematic diagram based on a PID algorithm;

FIG. 2: the invention relates to a control method flow chart of a transient electromagnetic transmitting system based on a PID algorithm;

FIG. 3: the invention is a waveform diagram of current flowing through a load coil;

FIG. 4: the invention relates to a closed-loop control block diagram of emission current.

In the figure: 1. the device comprises a transmitting system, 2, a main control circuit, 3, an optical coupling switch, 4, an H bridge circuit, 5, a Hall sensor, 6, an analog-to-digital converter, 7 and a load coil.

Detailed Description

Please refer to fig. 1, fig. 2, fig. 3, and fig. 4.

The invention relates to a transient electromagnetic transmitting system 1 based on a PID algorithm, which comprises a main control circuit 2, an optical coupler switch 3, an H bridge circuit 4, a Hall sensor 5, an analog-to-digital converter 6 and a load coil 7, wherein the main control circuit 2 sends out weak current signals, the weak current signals are converted into strong current signals through the optical coupler switch 3, the H bridge circuit 4 is driven to be opened and closed, current signals are formed in the load coil 7 and are transmitted back to the H bridge circuit 4, and a closed loop is formed; the hall sensor 5 collects analog signals flowing through the load coil 7, the analog signals are converted by the analog-to-digital converter 6, and digital signals are fed back to the main control circuit 2. The optical coupling switch 3 is connected with the main control circuit 2 and controls an H bridge circuit 4, and two paths of output ends of the H bridge circuit 4 are respectively connected with an inlet and an outlet of the load coil 7 to form a closed loop; the Hall sensor 5 is sleeved on the load coil 7, and the analog-to-digital converter 6 is connected with the main control circuit 2 and the Hall sensor 5.

In this embodiment, the optical coupler switch 3 is a photoelectric coupler, so as to realize isolation of strong current and weak current. The H bridge circuit is composed of 4 MOS tubes.

The invention provides a transient electromagnetic emission control method based on a PID algorithm, which comprises the following steps:

step one, initializing a main control circuit 2, and configuring a waveform curve to be output, wherein the waveform curve comprises current magnitude, frequency, duty ratio and current turn-off time.

In this embodiment, the core of the main control circuit 2 selects a DSP chip, configures an output waveform curve according to actual detection requirements, divides a cycle into a plurality of discrete time points, connects a rising edge, a flat top section, and a falling edge of a current curve into a linear waveform related to the discrete time, where the flat top section is a fixed current value, and the rising edge and the falling edge are current turn-on and turn-off times. In this embodiment, the discrete point time interval of the rising edge and the flat top segment is 100us, and the discrete point time interval of the falling edge is 5 us. The configured current waveform is a bipolar square wave with a duty ratio of 50% and a current waveform of less than 50A, and the turn-off time is generally more than 1 ms.

And step two, the main control circuit 2 emits high-frequency PWM waves, the frequency of the PWM waves is larger than 100kHz, the optical coupler switch 3 drives the switch of the H bridge circuit 4, and current waveforms are obtained on the load coil 7.

And step three, the Hall sensor 5 is arranged on a load coil 7 loop, collects the current waveform flowing through the load coil 7 in real time, collects the current value by using the high-speed analog-to-digital converter 6, collects the current value at the same time, the collection frequency of the high-speed analog-to-digital converter 6 is 1MSPS, and the high-speed analog-to-digital converter 6 communicates with the main control circuit 2 through the SPI serial peripheral interface to feed back data to the main control circuit 2.

And step four, the main control circuit 2 compares the current value and the feedback current value at the moment, a PID controller embedded in the main control circuit 2 is used for adjusting the duty ratio of the output PWM wave, the optical coupling switch 3 is used for controlling the opening and closing of the H bridge circuit 4 to reduce the difference between the feedback current value flowing through the load coil and the configuration value, and the current waveform matched with the configured curve is obtained on the load coil 7.

As shown in the closed loop control block diagram of the present invention in fig. 4, the open loop transfer function of the coil load can be expressed as:

G(s)＝R+Ls

the time domain form of the PID controller can be expressed as:

e[t]＝i_r(t)-i₀(t)

in the formula: i.e. i_r(t) represents a standard current value, i₀(t) represents the current value at this time, e [ t ]]Represents the current deviation u [ t ]]Representing the output PWM wave duty cycle. R represents a resistance value of the load coil 7, and L represents an inductance value of the load coil 7.

The discretization of the PID controller can be expressed as:

u[n]＝k_pe[n]+k_i{e[n]+e[n-1]+e[n-2]+...}+k_d{e[n]-e[n-1]}

e[n]＝i_r(n)-i₀(n)

in the formula: i.e. i_r(n) represents a value of arrangement current, i₀(n) represents the sampled current value, e [ n ]]Representing the current deviation at that moment, u n]Representing the output PWM wave duty cycle. By pair k_p、k_i、k_dThe three parameters are adjusted to control the response characteristic of the transmitting system, and the current waveform matched with the configured curve can be obtained.