Research On Smooth Motion Tracking Control Method Of Drilling Fluid Continuous Wave Generator

High precision control of drilling fluid continuous wave generator is the key to realize the precise generation of downhole continuous wave shape.At present,the domestic related technology is not mature.It is of great significance to carry out relevant research to break the foreign monopoly and develop the drilling fluid continuous wave technology with independent property rights in China.This paper aims at producing precise downhole continuous wave shape and focuses on the high precision control of drilling fluid continuous wave generator,and studies the following:(1)the research on smooth modulation of continuous wave signal of drilling fluid.Based on the characteristics of continuous wave signal modulation in drilling fluid,a smooth modulation method based on phase shift keying is proposed.A smooth modulation model is established.The theory and CFD simulation are used to reveal the characteristics of smooth continuous wave signal and the corresponding rotary valve movement.(2)Analysis of load torque characteristics of continuous wave generator.Based on the finite element and fluid momentum theory,the load torque analysis model is established.The correctness of the model is verified by CFD analysis and experimental comparison.The load torque characteristics of DFCW generator under different drilling fluid displacement are analyzed.(3)The establishment of the method of liquid magnetic co compensation.Based on the load torque characteristics,a liquid magnetic cooperative compensation method is proposed,and the load compensation device is designed,and the rationality of the design is verified by finite element analysis.(4)The research of smooth motion tracking control method.Based on the smooth modulation method,the position current double loop high precision position tracking control system is designed,and the feasibility of the control system design is verified by simulation and comparison.(5)The design and experimental verification of control hardware and software.Based on the control principle and smoothing modulation method of PMSM,the control hardware and software are designed.The feasibility of the design of the software and hardware is verified by no load experiment of the motor.The robustness of the control system is verified by the simulated load experiment,and the rationality of the design of the smooth motion tracking system is verified by the ground hydraulic experiment.Through the above research,the following conclusions are obtained:(1)the smooth modulation method can realize the continuous wave signal phase modulation under the smooth motion of the driving motor,(2)the load torque has the characteristics of periodicity and strong alternation,and the amplitude increases with the increase of drilling fluid displacement,(3)the liquid magnetic collaborative compensation method can greatly reduce the load torque of the driving motor output end,(4)the smooth motion tracking control system can be realized,(5)the experimental results show that the smooth motion tracking control method can realize the precise generation of continuous wave waveform in the actual hydraulic environment.The research results can provide theoretical reference for the design of rotary valve continuous wave generator in China.