Research On The Control Algorithm And Signal Processing Method Of Continuous-wave Pulser

The continuous development of MWD technology has largely promoted the drilling technology.However,the quantity of the measured downhole data has increased so fast that the data transmission rate cannot keep pace with it.The continuous-wave pulser came into being.This thesis is focused on the motor control strategy and signal processing method based on the self-developed continuous-wave pulser.Firstly,the current development status of MWD/LWD is introduced,it is very necessary to develop our own patents of continuous-wave pulser.Then,the mechanical structure,the encoding method and the signal modulation are introduced thereafter.Secondly,the application of Active Disturbance Rejection Control(ADRC)on the motor control is presented.The pulser suffers from dynamic and hydraulic load and the PID controller cannot work well.For a good performance of the motor speed control,the ADRC is applied.Both the theory analysis and the model simulation show that the second order LADRC performs better than PID.Then,the laboratory water circulating tests were carried out based on the self-developed continuous-wave pulser.The main control chip TMS320F28335 received data from MWD tube and encoded the data according to the predetermined rule.The pulser rotated according to the encoded sequences.The pressure signal was detected by the ground transducer and send to the upper computer.The result shows that the whole system works well and the data transmission speed can reach 6 bps.Lastly,the zero-crossing detection technique,the Hilbert transform and the cross correlation method were used in the signal processing.The cross correlation detection was chose as the practical method for the on-line signal processing of the 2FSK mud pulse signal.