Research On Position Tracking Control System Of Bldcm For The Logging With Drilling

In order to meet the actual requirements of the brushless DC motor position tracking system applied to oil well logging, this paper studies the simulation of the control strategy of this system and realizes this position tracking by using Iterative Learning control strategy. Hardware circuit is designed and software implementation algorithm is written based on the hardware, which can make the motor track the reference signal.For the needs of tracking the reference position signal, indirect cascading Iterative Learning control is selected as the position tracking algorithm. Firstly we design a local three-close-loop PID controller, establish its simulation model and analyze the property of this system. Based on above, Iterative Learning control modules are cascaded and the error in the position tracking Iterative Learning control law is modified. By studying the simulation model of the Iterative Learning control, we can verify that this Iterative Learning law can efficiently reduce the error in the process of position tracking. By comparing and analyzing the results of open-loop and close-loop, we can conclude the property of close-loop Iterative Learning control strategy is better,this paper combine the effect of the two module togetherThe error of position tracking can be reduced efficiently after several iterations, but it is time-consuming and the learning rate is slow. In order to satisfy the requirements of the actual system, the Iterative Learning algorithm needs to be optimized and the learning rate needs to be improved. Firstly the learning gain of the fixed gain Iterative Learning law is optimized by simulation analyses, through which the relationship between learning gain and learning rate is observed. Secondly exponential variable gain Iterative Learning law is adopted and by simulation analyses, it is verified that the Iterative Learning law can accelerate the learning rate. On this basis, discrete exponential variable gain Iterative Learning is proposed, and all the parameters are determined by simulation analyses.For the requirements of the brushless DC motor position tracking system applied to oil well logging, we design related hardware circuit, and it mainly includes the kernel control circuit based on DSP, position signal acquisition circuit, current sampling circuit, MOSEFET power drive circuit and SCI communication circuit. On the basis of the hardware, the software system is designed and it includes Iterative Learning control module, three-close-loop PID control module, SCI communication module, motor soft-start module, SPI position signal acquisition module, etc.Finally, position tracking control system is tested by experiment and the results shows that the brushless DC motor system can realize reference position signal tracking and teal-time serial communication with the upper computer. This system is compatible with other modules to achieve related functions as oil well logging tools.