Design Of Motor Drive Controller For Downhole Four-arm Pusher

As a reserve resource,oil has great strategic significance,and its stable exploitation is an important factor affecting the progress and development of country.Well logging technology is the key technology for oil exploration,and it is updated and progressed due to the needs of the country.Well diameter logging is an important means to understand downhole lithology and ensure logging safety.Downhole four arm pusher is a key device for well diameter measurement combined with azimuth instrument,which assists in well diameter measurement.Starting from the stable pusher drive,this thesis studies the design of the motor drive controller of the four-arm pusher in the well,and mainly discusses the overall scheme design,PID control algorithm design,hardware circuit design and software program design of the motor drive controller for the four-arm pusher downhole.The design work of the overall plan starts from the working principle of the downhole four-arm pusher,combined with the workflow of the well caliper measuring instrument to analyze the design requirements of the motor drive controller of the downhole four-arm pusher.The design scheme of PID control algorithm,hardware circuit and software program is then determined.And so is the overall work flow of the motor drive controller of the four-arm pusher downhole.The design work of PID control algorithm is based on the working requirements of stable pushing of the four-arm pusher in the well.Based the permanent magnet brushless DC motor with higher power density,the PID control algorithm is realized.And the three closed-loop PID controller composed of current loop,speed loop and position loop is designed.The simulation model is designed and verified in SIMULINK,and a control strategy with certain reliability is given.In the hardware circuit design,according to the workflow of the motor drive controller of the four-arm pusher in the well,the controller framework with DSP as the control core is determined.The hardware circuit includes the main control circuit of the drive controller,the bus filter circuit,the voltage conversion circuit,the current adoption circuit,the overcurrent protection circuit,the power drive circuit,and the communication circuit with the logging controller.According to the hardware circuit,the software program design scheme is determined.The software program mainly includes the main program design,motor control program,soft start program,rotor commutation program,PID control subroutine and communication program with logging controller.Finally,an experiment to test the control function and communication function of the motor drive controller of the four-arm pusher in the well is designed in this thesis.The system is jointly debugged,and the debugging effect is analyzed.The experimental results show that the design of the motor drive controller of the downhole four-arm pusher conforms to various design indexes,and meets the design requirements of stable position tracking.