A wide-range ac-dc power conversion system and method for drilling wireless LWD

Abstract

The invention discloses a wide-range AC-DC power conversion system and method for a wireless drilling tool while drilling, comprising: a three-phase rectifier circuit is connected to a filter and voltage equalizer circuit for rectifying and filtering a three-phase AC voltage and then outputting a DC voltage The filter equalizing circuit is connected with the double-sided double BUCK PWM conversion circuit, the double-sided double BUCK PWM conversion circuit is connected with the impulse voltage regulator transformer, and the double-sided double BUCK PWM conversion circuit includes a first MOS tube, a second MOS tube, and a drive circuit and PWM conversion circuit; the first MOS tube and the second MOS tube are respectively connected between the positive pole and the midpoint voltage of the filter equalizing circuit, and between the midpoint voltage and the negative pole, and the double MOS tube is controlled by the driving circuit and the PWM conversion circuit. When the dual MOS transistors do not act synchronously, the two-sided coils of the impulse voltage stabilizer transformer generate induced voltages with the same voltage and opposite polarity, so that the dual MOS transistors maintain half voltage, so as to output the target voltage after PWM modulation of the DC voltage. The AC50-500V voltage output by the underground three-phase generator can be converted into AC-DC and work stably.

Description

technical field [0001] The invention relates to the technical field of a wireless while-drilling system for oilfield drilling, in particular to a wide-range AC-DC power conversion system and method for a wireless drilling-while-drilling instrument in drilling. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] In the process of oilfield drilling, there are spectral measurement and rotary steering systems in the wireless while drilling system. These two systems must be powered by high-power power supplies, and this power supply can only be achieved by using downhole generators. However, the driving force of the downhole generator comes from the circulating mud flow during drilling, and its flow rate and pressure depend on the working state of the mud pump, which causes the output voltage of the downhole generator to fluctuate greatly. In the a...

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Problems solved by technology

However, the driving force of the downhole generator comes from the circulating mud flow during drilling, and its flow and pressure depend on the working status of the mud pump, which causes the output voltage of the downhole generator to fluctuate greatly. In the actual test, it is AC50-500V. The devices in the AC-DC conversion circuit put forward extremely high requirements. For example, the withstand voltage of the filter capacitor reaches 600V at 125°C, the withstand voltage of the MOS tube in the PWM circuit reaches 1200V, and the current withstand voltage of the high-temperature capacitor is generally 400V. The ultimate withstand voltage of the silicon MOS tube is 950V, and the withstand voltage of the silicon carbide MOS tube can reach 1200V, but the price is several thousand yuan each

If a low-voltage, high-current generator is too large to install, a high-voltage generator needs to be stepped down by an AC transformer first, which not only has low efficiency, but also causes temperature rise, and is too large to be installed in the drill pipe.

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