Research On The Reliability Design And Control Algorithm Of Continuous Wave Pulser

The continuous wave pulser is important to measurement while drilling(MWD)system,which is correlated with the high data transmission,high reliability and anti-interference ability.The continuous wave pulser is driven by the permanent magnet synchronous motor(PMSM),which is the core part of the pulser.In this thesis,the fault diagnosis and protection scheme for continuous wave pulser drive motor was designed to ensure its reliability,and the control algorithm of continuous wave pulser was designed,simulated and tested.Firstly,the current research status of the continuous wave pulser and the motor fault diagnosis and protection technology were introduced.The working principle of the continuous wave pulser and the basic theory of common control algorithm were explained.Secondly,the main fault types and characteristics of PMSM were introduced.The common fault diagnosis and protection scheme was specifically designed: for rotor eccentricity fault,the occurrence of fault was diagnosed by using wavelet transform,and the feasibility was verified by simulation;for current fault,overcurrent protection combined with definite time and inverse time limit was adopted;for voltage fault,definite time limit protection was used;for the stator winding inter-turn short circuit fault,the mathematical model of PMSM under normal conditions was analyzed,and the winding resistance and inductance parameters under fault condition were calculated.The mathematical model of PMSM under the inter-turn short circuit fault was established,and the fault motor model was built in Simulink.According to the simulation results,the diagnosis and protection scheme of the short circuit fault based on the negative sequence current was designed.Thirdly,To elimate the effect of hydraulic torque on continuous wave pulser and to meet the signal transmission requirements,PID control algorithm,first order linear active disturbance rejection control algorithm,second order linear active disturbance rejection control algorithm,first order integral sliding mode control algorithm and second order integral sliding mode control algorithm were used to control the system.The basic principles and design schemes of the five control algorithms were introduced.The simulation model was built based on Simulink.Five kinds of control algorithms were tested under no load and load.Finally,the experiment platform of continuous wave pulser was designed,and the monitor with fault diagnosis function was developed,some electrical faults were simulated to verify the reliability of the protection method.And then the downhole stress state of the continuous wave pulser was simulated by using the platform,the control algorithms were tested under no-load and load,and the experimental results were compared and analyzed.The test provided the project design and parameter tuning method for the practical continuous wave pulser control algorithm.