New Electromagnetic Transmitter for EM-MWD System Based on Embedded RTOS: uc-OS III

A downhole electromagnetic transmitter is an important part of the EM-MWD telemetry, which is transmits low frequency electromagnetic waves to the ground to obtain downhole information. In this paper, a novel transmitter of EM-MWD telemetry is developed. Firstly, the hardware platform is well constructed with TMS320F2S12 controller; Secondly, a voltage and current loop PI (Proportional-Integral) controller for PWM (pulse width modulation) downhole electromagnetic transmitter is built by root-locus method. Finally, the crucial technic of transmitter of EM-MWD tool based on Embedded RTOS: uc-OS III is researched in detail. Simulation results show that the proposed downhole electromagnetic transmitter can work well in downhole complex environment narrow with batteries. The voltage and current loop PI PWM (pulse width modulation) downhole electromagnetic transmitter control can achieve low total harmonic distortion under linear loading condition, small steady state error and good dynamic response under any disturbance change in load. The developed downhole electromagnetic transmitter based on Embedded RTOS: uc-OS III can be used for EM-MWD and LWD system designs as well as the improvement of these systems performance through optimization studies.