Research On Control System Of Bldcm For The Logging With Drilling

In order to meet the actual requirements of fixed position and steady speed ofthe logging while drilling, according to the study of hardware design, simulationresearch and software algorithm, the article completes the design of the system,presents an improved variable parameter PID control strategy and completes thesoftware algorithm, realizes the communication between the upper machine andcontrol system.To the control system’s requirements of fixed position and steady speed, thearticle studies the characteristics of bipolar and unipolar control of the traditionalbrushless DC motor control, and the two-loop control and three-loop controlthrough simulation, eventually establishes a bipolar tricyclic control of the controlprogram. Meantime the control system uses different PID control strategy for thedifferent ring, it makes flexible use of a combination of variable parameter PIDcontrol，discrete PID control and PID with dead zone control.For the position accuracy of the control system is less than one radian, thearticle studies the deficiencies of traditional absolute position count and relativeposition count, and puts forward a new count based on pulse edge. In order toachieve high-precision location positioning requirements, the position controlmethod achieves the separation control of integer ring and decimal ring, and can gethigh accuracy of the position feedback value.According to the environment of the control system, and enhance the reliabilityof the system. the article designs the temperature monitoring and current protectioncircuit, in the meantime realizing the communication between control system withthe host computer by the use of RS485serial communication, and it ensure that agroup control system operation data will be upload every200ms, to real-timeachieve the requirements of monitoring control system performance.the control system puts forward an on-line programming control algorithm,which would achieve the online update by the use of serial communication software,to solve the issue that the control system functions need to be improved constantlyand the program can be real-time updated. By using this method we could downloadthe program required to the control chip in the form of a packet, and it only needstwo serial communication lines, the RS232serial communication and does not needto open the equipment’s shell. The experimental results show that by the use ofonline programming to update the system software can not only update the systemsoftware accuracy，but also avoid the dismantling and reinstalling of the equipment, so it both cost savings and improve the working life of the system.Finally，the system tested by the experiment, the experimental results show thatthe position control system of the logging while drilling can control the brushlessDC motor working stable, positioning accurate under extreme load conditions, andthe control system could meet the requirements that positioning accuracy is withinone degree, while in the case of extreme pressure, and the steady speed range up toa500-4000r/min of the requirements; the system also can real-time realize thecommunication with the host computer, the communication is obtaining the controlinstructions and upload the operating data, so that online programming functions isachieved, and the program’s online programming is completed.