Research On Non-contact Power Conversion Technology For Downhole Power Supply Equipments

The slurry generator provided power for the eletric motors in the powerdrive system. This powerneeded to be sent from rotating part to non-rotating part. The article designed a complete set ofcontactless inductive coupled power transfer (ICPT) system, which can meet the wide-range input andstable output.This paper analyzed several system constitution methods, and chose the contactless inductivecoupled power transmission system with the voltage regulator in the load side. System consisted offour parts: high-frequency inverter, separate transformer, rectifier and regulator.Through analyzing the magnetic circuit, the equivalent circuit model and the compensationcircuit of the detachable transformer, the paper designed a separated transformer for the non-contactpower transmission system of the downhole. The inverter used series resonant full-bridge structure.By analyzing the equivalent circuit of the inverter, the paper obtained the best transmission conditionsand the optimal transmission. Paper compared two kinds of control circuit which used UC1842andCD4046respectively. The theoretical analysis and experimental waveforms showed that the frequencytracking circuit which based on the PLL principle was much better for the system. The DC-DC part inthe load side used the dual interleaved active-clamp forward converter controlled by the LM5034.Auxiliary power used UC1842to control the flyback circuit.To improving the transmission efficiency, the paper studied the under oil-well contactlessinductive closed-loop transmission system theoretically, designed the hardware and software.Hardware system consisted of three parts, the main circuit which used phase-shifted full-bridgestructure; control circuit consisted by UC3875and the feedback circuit which used contactlessinductive signal transmission technology. The author used SABER to simulate the operation of thephase-shifted full-bridge circuit.The experiments of the prototype showed that: under the wide-range input voltage, the output ofthe contactless inductive power transmission system in the downhole was stable, and the transferefficiency could get75%, met the design requirements. The transfer efficiency of independentstructures could get85%. The system met the requirement of stability, reliability and could workunder high temperature environment.