Research On The Control Strategy Of Variable Resistance Torque Of The Drive Motor On Continuous Wave Mud Pulse

With the development of drilling technology,more and more downhole parameters need to be measured and be transfered to the ground quickly and effectively.Continuous wave mud pulse has advantages of moderate cost,reliable performance,simple manufacturing process,high transmission rate and great application prospect.But currently the technology is monopolied by several foreign companies,the product can only be rent but not for sale.At present,compared to the continuous wave pulse,the positive pulse,which is widely used in our country,whose transmission rate is too low to meet the growing demand of drilling operations.Therefore,it's of great significance to study the continuous wave pulse to break the monopoly of foreign technology,to formate independent intellectual property rights products,and to improve the measurement while drilling technology level of our country.By controlling the drive motor,the continuous wave pulse's rotary valve rotary in high-speed to change the mud circulation area,resulting in continuous pressure pulse carrier signal,then the downhole measurement information is modulated onto the mud pressure pulse carrier to realize the data transmission with high speed.In this paper,the control system of drive motor and the rotary valve are modeled and simulated,and the data transmission process of continuous wave pulse is simulated by frequency shift keying and coherent demodulation.The simulation results show that,when the influence of hydraulic torque is considered,it can be correctly demodulated when the performance of the bandpass filter is extremely good;When consider the channel noise,the performance of the filter is difficult to be improved,and the PI control strategy can not be properly demodulated.Therefore,the sliding mode control is used to improve the dynamic performance of the motor,so that the correct demodulation is achieved.Both improving the dynamic performance of the drive motor when considering research control strategies and improving the denoising performance when getting signal reception have benefits for improving the quality of signal transmission,which is of great reference value for manufacturing continuous wave pulse.