A dual circuit motor type mud pulse generator

Abstract

The application discloses a double-loop motor type mud pulse generator, which comprises a pulse generator, a driving short section, a battery cylinder short section and a probe pipe short section which are sequentially connected; the pulse generator comprises an outer pipe, a circuit converter, a motor box, a motor reducer, a stator and a rotor and a torque sensor which are sequentially arranged in the outer pipe; a double-loop brushless DC motor is arranged in the motor box; an overcurrent channel is arranged on the stator and the rotor; the driving short section can control the pulse generator to generate cyclic mud pulse fluctuation. The motor compensation loop is used for synchronizing the mud liquid flow rate, reducing the disturbance caused by the nonlinear factors such as mud liquid impact on the pulse generator, ensuring that the rotating valve driven by the output shaft of the motor position loop accurately and rapidly tracks the instruction signal sent by the driving short section, and inhibiting the distortion of the output waveform of the pulse generator, so that the difficulty of signal filtering and identification in the ground decoding link is obviously reduced.

Description

Technical Field

[0001] This invention belongs to the field of coal mine drilling engineering technology, and relates to a continuous wave mud pulse generator in a wireless drilling measurement device, specifically a dual-loop motor-type mud pulse generator and its control method. Background Technology

[0002] During directional drilling in coal mines, facing the explosive environment of high dust, high gas, and high humidity underground, operators typically use mining measurement-while-drilling (MWD) devices to obtain engineering and geological parameters. MWD data transmission includes both wired and wireless methods. Wired MWD signals have poor reliability over long distances, limited transmission distance, and high requirements for drilling tools. Wireless MWD devices primarily use signal transmission methods such as acoustic waves, electromagnetic waves, mud pulses, and smart drill pipes, with mud pulse transmission being the most stable and reliable. Mud pulse methods include positive pulses, negative pulses, and continuous wave pulses. Currently, positive mud pulse MWD is the primary method used in underground coal mine drilling operations. While it overcomes the problems of wired MWD systems, its transmission rate is low, and with technological advancements, it is no longer sufficient to meet the demands of long-distance, high-volume data transmission.

[0003] Continuous wave pulse measurement while drilling (CWDM) systems have the advantages of fast response and large data transmission capacity, but they also have problems such as complex technical routes and difficulty in pulse signal identification.

[0004] In continuous wave transmission mud pulse measurement-while-drilling (MWD) systems, the pulse generator requires a permanent magnet synchronous motor rotor to drive a valve or blade to rotate within the mud. During system operation, the rotor oscillates at high frequency following a sinusoidal position signal to generate mud pressure pulses. This requires high precision in tracking the control signal. However, complex nonlinear factors exist in the mud impact, the mechanical characteristics of the transmission mechanism, and the electrical characteristics of the motor itself, making accurate mathematical modeling difficult. In some cases, these nonlinear factors significantly impact the pulse generator's performance. On one hand, under mud impact conditions, if the rotary valve driven by the motor output shaft cannot accurately and quickly track the command signal, the hydraulic torque will distort the continuous waveform output by the pulse generator, increasing the difficulty of signal filtering and identification in the surface decoding stage. This leads to a large deviation between the information transmitted back to the surface and the actual measurement information, hindering effective formation assessment. On the other hand, to ensure the pulse generator has good environmental adaptability and can be applied to different depths, types of mud, and different mud flow rates, the rotary valve control system should possess good dynamic performance and robustness under various conditions. Currently, there are few studies on modulation and demodulation of mud pulse data transmission systems that focus on improving the motor's structure and control strategies to reduce disturbances. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a dual-loop motor-type mud pulse generator to reduce the distortion of the continuous waveform output by the pulse generator caused by mud impact during operation. Furthermore, it addresses the inherent anti-disturbance structure of the permanent magnet synchronous motor used in the mud pulse generator during drilling measurement and its associated servo control strategy, minimizing disturbances caused by hydraulic torque and resolving issues such as decreased motor following accuracy due to mud impact at different flow rates.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A dual-loop motor-driven mud pulse generator includes a pulse generator, a drive section, a battery sleeve section, and a probe section connected in sequence. The pulse generator includes an outer tube, a circuit converter, a motor housing, a motor reducer, a stator and a rotor connected in sequence inside the outer tube, and a torque sensor located on the inner wall of the outer tube; the motor housing contains a motor, which is a dual-circuit brushless DC motor; the stator has multiple stator overcurrent channels, and the rotor has multiple rotor overcurrent channels. The drive short section energy-saving control pulse generator produces circulating mud pulse fluctuations; the probe short section is used for measuring and storing borehole trajectory parameter data, and sends instructions and data to the drive short section according to the set program to control the operation of the system; the battery sleeve short section provides DC power to the entire system.

[0008] The present invention also includes the following technical features: Specifically, the circuit converter includes an outer ring and an inner ring. The outer ring is fixed to the inner wall of the outer tube. A wire bridge connects the inner ring and the outer ring. A fan-shaped current channel is formed between adjacent wire bridges. End caps and a central connector are installed at the front and rear ends of the inner ring, respectively. A guide ring is sleeved on the outer ring. Insulated wires in the wire bridges connect the guide ring and the central connector. An axial wire hole is provided in the side wall of the outer tube, and a communication cable in the wire hole connects the guide ring and the torque sensor.

[0009] Specifically, the stator has a disc-shaped structure and is fixed to the inner wall of the outer tube by multiple positioning holes and bolts on its outer wall. The stator has a central through hole in the center, through which the rotor can pass. The stator has four stator flow channels evenly distributed in a 90° circle, and the stator flow channels are fan-shaped.

[0010] Specifically, the rotor includes an outer ring of the rotor bearing, bearing balls, and an inner disk of the rotor bearing arranged from the outside to the inside. The inner disk of the rotor bearing is provided with multiple rotor flow channels. The center of the inner disk of the rotor bearing is a drive shaft, which is connected to the motor position output shaft through a motor reducer.

[0011] Specifically, the left end of the motor housing is fixed to the outer tube of the pulse generator with screws, and there is an annular gap between the motor housing and the inner wall of the outer tube to allow the mud to pass through; the motor housing includes a motor shell and a dual-circuit brushless DC motor inside; the dual-circuit brushless DC motor adopts a dual-circuit structure with a compensation circuit and a position circuit connected coaxially; the compensation circuit includes a compensation circuit rotor and a compensation circuit stator, the compensation circuit rotor is radially limited to the motor shell by ball bearings, and the compensation circuit stator is fixed to the motor shell by bolts; the position circuit includes a position circuit rotor and a position circuit stator, the position circuit rotor is radially limited by ball bearings, and the position circuit stator is fixed to the motor shell by bolts; the left end of the compensation circuit rotor... A rotary encoder is connected to the end of the position loop rotor, and a position output shaft is connected to the right end of the position loop rotor. A coaxial spring rod is provided between the compensation loop rotor and the position loop rotor. The compensation loop stator and the position loop stator generate magnetomotive forces, wherein the magnetomotive force of the position loop stator interacts with the magnetic field of the position loop rotor to output a position signal. The compensation loop rotor moves with the circumferential angular position of the hydraulic torque to compensate for the position difference between the motor shaft and the hydraulic torque, thereby achieving synchronous position control of the two loops. The compensation loop rotor drives the position loop rotor to move with it through the spring rod and reduces the disturbance caused by the coupling effect between the two loops. The rotary encoder, as an angle sensing device, measures the number of pulses to obtain the angular position signal output by the position loop.

[0012] Specifically, the probe section includes an outer cylinder, inside which are installed an orientation sensor assembly and a main control module. The main control module is used to control the pulse generator to work, and the orientation sensor assembly is used to collect attitude parameters and calculate the spatial attitude of the probe section. The main control module sends the attitude parameters to the drive section, and the drive section controls the pulse generator to generate circulating water pulse fluctuations.

[0013] A servo control method based on the aforementioned dual-loop motor-type mud pulse generator includes the following steps: Step 1: The torque sensor installed on the inner wall of the outer pipe measures the mud flow rate, calculates the circumferential position signal of the torque disturbance under the current working state based on the flow function, and sends the position disturbance signal to the compensation circuit. Step 2: The compensation loop receives the position disturbance signal, compares it with its own position, calculates it, and then outputs the control quantity to the motor driver. Based on the continuously adjusted closed-loop control calculation, it achieves high-precision real-time motion tracking of hydraulic torque and sends the compensation signal to the position loop. Step 3: The compensation circuit uses the position circuit as a load to drive it and keep it moving synchronously on the same axis. At the same time, it provides a reaction force to the position circuit to ensure its continuous operation. Step 4: The probe section measures and calculates the attitude parameters. The collected data is encoded according to the mud pulse coding algorithm and converted into a command signal for the position loop. The rotary encoder feeds back the position information output by the system to the position loop. By comparison, the calculated control quantity is output to the motor driver installed in the drive section, which drives the rotor control pulse generator of the position loop to generate circulating water pulse fluctuations. The mud fluid transmits data to the ground in the form of pressure waveforms. The ground host computer processes the data.

[0014] Compared with the prior art, the present invention has the following technical effects: In the present invention, a dual-circuit motor-driven mud pulse generator for coal mines and its working principle, the flow rate of the mud is synchronized through a motor compensation circuit, which effectively reduces the disturbance caused by nonlinear factors such as mud impact on the pulse generator. This ensures that the rotary valve driven by the output shaft of the motor position circuit accurately and quickly tracks the command signal sent by the drive section, thereby suppressing the distortion of the output waveform of the pulse generator and significantly reducing the difficulty of signal filtering and identification in the ground decoding stage.

[0015] This invention adds a spring rod link between the two circuits of the motor, which serves as a coaxial connection while reducing the disturbance caused by the coupling between the two circuits, and further reduces the impact of nonlinear factors on the overall system. This invention relates to a servo control method based on a dual-loop motor-type mud pulse generator. It uses a flow channel torque sensor and a motor output shaft position sensor to collect mud flow information and motor position information in real time, forming a closed-loop servo control. This method ensures the dynamic performance of the overall system while also meeting the environmental adaptability requirements of the system under different working conditions, and has good robustness. Attached Figure Description

[0016] Figure 1 This is the overall structure of the wireless measurement while drilling system according to an embodiment of the present invention; Figure 2 The structure of the dual-loop motor-type mud pulse generator is shown in this embodiment of the invention. Figure 3 This is an overall cross-sectional view of the dual-circuit brushless DC motor according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the synchronous servo control principle of a dual-loop brushless DC motor according to an embodiment of the present invention. Figure 5 This is a block diagram of the servo system control for a dual-loop motor-type pulse signal generator according to an embodiment of the present invention.

[0017] Figure 6 This is a schematic diagram of the control software composition of a dual-loop motor-type pulse generator according to an embodiment of the present invention.

[0018] Meaning of the reference numerals in the attached diagram: 1. Pulse generator, 101. Circuit converter, 102. Motor housing, 103. Stator, 104. Rotor, 105. Torque sensor, 106. Outer tube, 107. Motor reducer, 1021. Rotary encoder, 1022. Compensation circuit rotor, 1023. Compensation circuit stator, 1024. Spring rod, 1025. Position circuit rotor, 1026. Position circuit stator, 1027. Position output shaft, 1028. Motor housing. Detailed Implementation

[0019] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0020] Example 1: like Figure 1 As shown, this embodiment provides a dual-loop motor-driven mud pulse generator, including a pulse generator 1, a drive section, a battery cylinder section, and a probe section connected in sequence.

[0021] like Figure 2 As shown, the pulse generator 1 includes an outer tube 106, a circuit converter 101 disposed inside the outer tube 106 and connected in sequence, a motor housing 102, a motor reducer 107, a stator 103 and a rotor 104, and a torque sensor 105 disposed on the inner wall of the outer tube 106; the motor housing 102 is equipped with a motor, which is a dual-circuit brushless DC motor; the stator 103 is provided with multiple stator current passages, and the rotor 104 is provided with multiple rotor current passages; the pulse generator is installed inside the main valve head drill collar, and the drive section, battery sleeve section, and probe section are installed inside the mining non-magnetic drill collar connected to the main valve head drill collar.

[0022] The drive short section energy-saving control pulse generator 1 generates circulating mud pulse fluctuations; the probe short section is used for measuring and storing borehole trajectory parameter data, and sends instructions and data to the drive short section according to the set program to control the operation of the system; the battery sleeve short section provides DC power to the entire system.

[0023] The circuit converter 101 includes an outer ring and an inner ring. The outer ring is fixed to the inner wall of the outer tube 106. A wire bridge is connected between the inner ring and the outer ring. There is a fan-shaped current channel between adjacent wire bridges. The front and rear ends of the inner ring are respectively equipped with end caps and a central connector. A guide ring is sleeved on the outer ring. The insulated wires in the wire bridge connect the guide ring and the central connector. An axial wire hole is provided in the side wall of the outer tube 106, and the communication cable in the wire hole connects the guide ring and the torque sensor 105.

[0024] The stator 103 has a disc-shaped structure and is fixed to the inner wall of the outer tube 106 by multiple positioning holes and bolts on its outer wall. The stator 103 has a central through hole through which the rotor 104 can pass. The stator 103 has four stator flow channels evenly distributed in a 90° circle. The stator flow channels are fan-shaped and the contour of the stator flow channels near the flushing liquid inflow end is chamfered by 5mm to form a flow guide groove structure with a flow guiding function. More specifically, the outer wall of the stator has three positioning holes evenly distributed in a 120° circle and is fixed to the outer tube by bolts.

[0025] The rotor 104 includes an outer ring of rotor bearings, bearing balls, and an inner disk of rotor bearings arranged from the outside in. The inner disk of rotor bearings has multiple rotor flow channels. A drive shaft is located at the center of the inner disk of rotor bearings, and the drive shaft is connected to the motor position output shaft via a motor reducer 107. Under normal circumstances, the flow channels between the rotor and stator are closed. The drive section sends pulse signals to the motor driver, controlling the motor position output shaft to rotate and cause a circumferential position difference between the rotor and stator. By changing the size of the internal flow area, pressure fluctuations are generated in the mud slurry within the flow channels, which are ultimately converted into pulse signals and transmitted to the ground.

[0026] like Figure 2 and Figure 3As shown, the left end of the motor housing 102 is fixed to the outer tube 106 of the pulse generator 1 by screws, and there is an annular gap between the motor housing 102 and the inner wall of the outer tube 106 to allow the mud to pass through; the motor housing 102 includes the motor housing 1028 and the dual-circuit brushless DC motor inside; the dual-circuit brushless DC motor is axially rigidly connected to the motor housing 102, the position output shaft is connected to the drive shaft, and the other end of the drive shaft is connected to the rotor to ensure that the servo motor power is stably transmitted to the rotor. The dual-circuit brushless DC motor adopts a dual-circuit structure with a coaxially connected compensation circuit and a position circuit. The compensation circuit includes a compensation circuit rotor 1022 and a compensation circuit stator 1023. The compensation circuit rotor 1022 is radially limited by ball bearings to the motor housing 1028, and the compensation circuit stator 1023 is fixed to the motor housing 1028 by bolts. The position circuit includes a position circuit rotor 1025 and a position circuit stator 1026. The position circuit rotor 1025 is radially limited by ball bearings, and the position circuit stator 1026 is fixed to the motor housing 1028 by bolts. A rotary encoder 1021 is connected to the left end of the compensation circuit rotor 1022, and a position output shaft 1027 is connected to the right end of the position circuit rotor 1025. A coaxial spring rod 1024 is provided between the position loop rotor 1022 and the position loop rotor 1025; the compensation loop stator 1023 and the position loop stator 1026 respectively generate magnetomotive force, wherein the magnetomotive force of the position loop stator 1026 interacts with the magnetic field of the position loop rotor 1025 as the output terminal to output a position signal; the compensation loop rotor 1022 moves with the circumferential angular position of the hydraulic torque to compensate for the position difference between the motor shaft and the hydraulic torque, so as to realize the position synchronization control of the two loops; the compensation loop rotor 1022 drives the position loop rotor to move with it through the spring rod 1024 and reduces the disturbance caused by the coupling effect between the two loops; the rotary encoder 1021 acts as an angle sensing device to measure the number of pulses to obtain the angular position signal output by the position loop.

[0027] The compensation loop rotor receives the circumferential position signal after the hydraulic torque is calculated, forming a position servo closed loop that moves synchronously with the hydraulic torque. The position loop rotor is coaxially connected to the compensation loop rotor via a spring rod, moving with the compensation loop rotor. Simultaneously, the spring rod adds a buffer between the compensation loop and the position loop, reducing the impact of the compensation loop's tracking error on the position loop. Internally, because the two loops are coaxially connected, the position loop moves following the compensation signal output by the compensation loop, making it a disturbed passive servo system. At the same time, the compensation loop is also affected by the torque disturbance generated by the position loop, resulting in mutual coupling between the two loops. Adding an elastic connection between the two motor loops allows the compensation signal generated by the compensation loop to be transmitted to the position loop via the spring rod in the form of a position servo. Adjusting the stiffness coefficient of the spring rod can reduce the disturbing torque generated by the coupling between the two loops. For a dual-loop system based on a PID controller, the stability condition of the system can be obtained by the Routh criterion. Therefore, the stiffness coefficient of the spring rod is inversely proportional to the proportional gain and integral gain. That is, as the stiffness coefficient increases, the forward gain of the system increases. Without affecting the speed and stability of the system, and without causing the system to oscillate due to excessive forward gain, the stiffness coefficient of the spring rod should be as large as possible.

[0028] The principle of eliminating hydraulic torque disturbance in the dual-circuit brushless DC motor of this invention is as follows: If the rotor of the compensation circuit can move synchronously with the circumferential hydraulic torque, then the movement of the hydraulic torque will theoretically not generate additional disturbance to the rotor of the position circuit. That is, when the output signal of the position output shaft of the dual-circuit brushless DC motor is zero at the pulse short section, it will not be affected by the disturbance torque caused by the hydraulic torque because it moves synchronously with the angular position of the hydraulic torque.

[0029] The probe section includes an outer cylinder containing an orientation sensor assembly and a main control module. The main control module controls the pulse generator 1 to operate, while the orientation sensor assembly collects attitude parameters and calculates the spatial attitude of the probe section. The main control module sends the attitude parameters to the drive section, which controls the pulse generator 1 to generate circulating water pulse fluctuations. The battery section provides power.

[0030] In this invention, the input commands of the dual-loop brushless DC motor include two items: one is the command sent by the drive sub, i.e., the position command of the position circuit; the other is the angular position signal calculated based on the hydraulic torque, i.e., the compensation command of the compensation circuit. Its output also includes two items: one is the compensation signal output by the compensation circuit to the position circuit according to the compensation command; the other is the position output signal of the position circuit, which follows the drive sub and is recorded and calculated by the rotary encoder. Therefore, the dual-loop brushless DC motor is a typical dual-input-dual-output system, where the two circuits are independent of each other yet mutually influential, such as... Figure 4As shown. When the system is working, the torque sensor at the rotary valve measures the current mud flow rate through the rotary valve channel and sends the calculated position disturbance signal to the motor compensation circuit. The motor driver controls the compensation circuit according to the continuously adjusted closed-loop signal to achieve real-time motion tracking of the hydraulic torque and sends the compensation signal to the position circuit. The probe section measures and calculates the current pulse command and sends it to the position circuit. At the same time, the rotary encoder feeds back the position signal output by the output shaft to the motor driver. After comparing and calculating with the pulse command, the motor driver issues a motor command to control the dual-loop motor to drive the rotary valve to change the channel area and output the final pulse signal.

[0031] Based on the above control principles, if the compensation loop is designed reasonably, i.e., the actual output corresponding to the hydraulic torque disturbance signal is zero, the disturbance effect of hydraulic torque on the pulse generator can be eliminated. In the control system of the electric mud pulse generator, the main control loop is the position loop, and the compensation loop can be regarded as a disturbance to the position loop. This application adopts the principle of structural invariance for compensation; to improve the performance of the control system, a position and velocity feedback method is introduced, which is fed back to the input end and compared with the output signal of the PID controller, which can increase the system damping and improve the dynamic performance of the system; to improve the system's response to the input and reduce the output phase lag, a command feedforward compensation link can be introduced at the command signal, such as... Figure 5 As shown.

[0032] like Figure 6 As shown, the control software for the dual-loop motor-type pulse generator consists of two parts: the user program runs under Windows, and the pulse generator real-time control program is based on the Ardence RTX kernel module, developed in C language, with a control cycle of 1 millisecond.

[0033] This invention employs a dual-loop structure motor-type mud pulse generator. One loop is a compensation loop, used to follow the position of the mud fluid hydraulic torque and reduce the distortion of the output pulse waveform caused by disturbances. The other loop is a position loop, which moves with the command pulse signal and corrects the position output in real time according to the compensation signal, forming a dual-loop servo closed-loop control.

[0034] In this invention, the two circuits of the brushless DC motor are coaxially connected by a spring rod, which reduces the coupling effect between the two circuits. At the same time, the stiffness coefficient of the spring rod can be adjusted according to the waveform demodulation and system speed requirements to change the system's anti-disturbance effect.

[0035] Example 2: This embodiment provides a servo control method based on a dual-loop motor-type mud pulse generator, including the following steps: Step 1: The torque sensor installed on the inner wall of the outer pipe measures the mud flow rate, calculates the circumferential position signal of the torque disturbance under the current working state based on the flow function, and sends the position disturbance signal to the compensation circuit. Step 2: The compensation loop receives the position disturbance signal, compares it with its own position, calculates it, and then outputs the control quantity to the motor driver. Based on the continuously adjusted closed-loop control calculation, it achieves high-precision real-time motion tracking of hydraulic torque and sends the compensation signal to the position loop. Step 3: The compensation circuit uses the position circuit as a load to drive it and keep it moving synchronously on the same axis. At the same time, it provides a reaction force to the position circuit to ensure its continuous operation. Step 4: The probe section measures and calculates the attitude parameters. The collected data is encoded according to the mud pulse coding algorithm and converted into a command signal for the position loop. The rotary encoder feeds back the position information output by the system to the position loop. By comparison, the calculated control quantity is output to the motor driver installed in the drive section, which drives the rotor control pulse generator of the position loop to generate circulating water pulse fluctuations. The mud fluid transmits data to the ground in the form of pressure waveforms. The ground host computer processes the data.

Claims

1. A servo control method based on a dual-loop motor-type mud pulse generator, characterized in that, A dual-circuit motor-driven mud pulse generator includes a pulse generator (1), a drive section, a battery cylinder section, and a probe section connected in sequence. The pulse generator (1) includes an outer tube (106), a circuit converter (101) disposed inside the outer tube (106) and connected in sequence, a motor housing (102), a motor reducer (107), a stator (103) and a rotor (104), and a torque sensor (105) disposed on the inner wall of the outer tube (106); the motor housing (102) is equipped with a motor, which is a dual-circuit brushless DC motor; the stator (103) is provided with multiple stator overcurrent channels, and the rotor (104) is provided with multiple rotor overcurrent channels; The drive short energy-saving control pulse generator (1) generates circulating mud pulse fluctuations; the probe short section is used for measuring and storing drilling trajectory parameter data, and sends instructions and data to the drive short section according to the set program to control the operation of the system; the battery sleeve short section provides DC power to the whole system; The left end of the motor housing (102) is fixed to the outer tube (106) of the pulse generator (1) by screws, and there is an annular gap between the motor housing (102) and the inner wall of the outer tube (106) to allow the mud to pass through; the motor housing (102) includes a motor shell (1028) and a dual-circuit brushless DC motor inside; the dual-circuit brushless DC motor adopts a dual-circuit structure of a compensation circuit and a position circuit connected coaxially; the compensation circuit includes a compensation circuit rotor (1022) and a compensation circuit stator (1023), the compensation circuit rotor (1022) is radially limited to the motor shell (1028) by ball bearings, and the compensation circuit stator (1023) is radially limited to the motor shell (1028) by ball bearings. 3) The position circuit is fixed to the motor housing (1028) by bolts; the position circuit includes a position circuit rotor (1025) and a position circuit stator (1026). The position circuit rotor (1025) is radially limited by ball bearings, and the position circuit stator (1026) is fixed to the motor housing (1028) by bolts; the left end of the compensation circuit rotor (1022) is connected to a rotary encoder (1021), and the right end of the position circuit rotor (1025) is connected to a position output shaft (1027); a coaxial spring rod (1024) is provided between the compensation circuit rotor (1022) and the position circuit rotor (1025). The compensation loop stator (1023) and the position loop stator (1026) generate magnetomotive forces respectively. The magnetomotive force of the position loop stator (1026) interacts with the magnetic field of the position loop rotor (1025) as the output position signal. The compensation loop rotor (1022) moves with the circumferential angular position of the hydraulic torque to compensate for the position difference between the hydraulic torque and the position of the two loops, thereby realizing the synchronous position control of the two loops. The compensation loop rotor (1022) drives the position loop rotor to move with it through the spring rod (1024) and reduces the disturbance caused by the coupling between the two loops. The rotary encoder (1021) acts as an angle sensing device to measure the number of pulses to obtain the angular position signal output by the position loop. The method includes the following steps: Step 1: The torque sensor installed on the inner wall of the outer pipe measures the mud flow rate, calculates the circumferential position signal of the torque disturbance under the current working state based on the flow function, and sends the position disturbance signal to the compensation circuit. Step 2: The compensation loop receives the position disturbance signal, compares it with its own position, calculates it, and then outputs the control quantity to the motor driver. Based on the continuously adjusted closed-loop control calculation, it achieves high-precision real-time motion tracking of hydraulic torque and sends the compensation signal to the position loop. Step 3: The compensation circuit uses the position circuit as a load to drive it and keep it moving synchronously on the same axis. At the same time, it provides a reaction force to the position circuit to ensure its continuous operation. Step 4: The probe section measures and calculates the attitude parameters. The collected data is encoded according to the mud pulse coding algorithm and converted into a command signal for the position loop. The rotary encoder feeds back the position information output by the system to the position loop. By comparison, the calculated control quantity is output to the motor driver installed in the drive section, which drives the rotor control pulse generator of the position loop to generate circulating water pulse fluctuations. The mud fluid transmits data to the ground in the form of pressure waveforms. The ground host computer processes the data.

2. The servo control method based on a dual-loop motor-type mud pulse generator as described in claim 1, characterized in that, The circuit converter (101) includes an outer ring and an inner ring. The outer ring is fixed to the inner wall of the outer tube (106). A wire bridge is connected between the inner ring and the outer ring. A fan-shaped current channel is formed between adjacent wire bridges. The front and rear ends of the inner ring are respectively equipped with end caps and a central connector. A guide ring is sleeved on the outer ring. The insulated wire in the wire bridge connects the guide ring and the central connector. An axial wire hole is provided in the side wall of the outer tube (106), and the communication cable in the wire hole connects the guide ring and the torque sensor (105).

3. The servo control method based on a dual-loop motor-type mud pulse generator as described in claim 1, characterized in that, The stator (103) is a disc-shaped structure. The stator (103) is fixed to the inner wall of the outer tube (106) by multiple positioning holes and bolts on its outer wall. The stator (103) has a central through hole in the center, through which the rotor (104) can pass. The stator (103) has four stator flow channels evenly distributed in a 90° circle, and the stator flow channels are fan-shaped.

4. The servo control method based on a dual-loop motor-type mud pulse generator as described in claim 1, characterized in that, The rotor (104) includes an outer ring of rotor bearing, bearing balls and inner disk of rotor bearing arranged from the outside to the inside. The inner disk of rotor bearing is provided with multiple rotor flow channels. The center of the inner disk of rotor bearing is a transmission shaft, which is connected to the motor position output shaft through a motor reducer (107).

5. The servo control method based on a dual-loop motor-type mud pulse generator as described in claim 1, characterized in that, The probe section includes an outer cylinder, inside which are installed an orientation sensor assembly and a main control module. The main control module is used to control the pulse generator (1) to work. The orientation sensor assembly is used to collect attitude parameters and calculate the spatial attitude of the probe section. The main control module sends the attitude parameters to the drive section, and the drive section controls the pulse generator (1) to generate circulating water pulse fluctuations.

Images