Wide-range AC-DC power supply conversion system and method for logging-while-drilling tool

Abstract

The invention discloses a wide-range AC-DC power supply conversion system and method for a logging-while-drilling tool. According to the system, a three-phase rectification circuit is connected with a filtering voltage-sharing circuit and is used for rectifying and filtering a three-phase AC voltage, and then outputting a direct-current voltage; the filtering and voltage-sharing circuit is connected with a double-side double-BUCK PWM conversion circuit; the double-side double-BUCK PWM conversion circuit is connected with an impulse voltage-stabilizing transformer; the double-side double-BUCK PWM conversion circuit comprises a first MOS tube, a second MOS tube, a driving circuit and a PWM conversion circuit; a first MOS tube and a second MOS tube are respectively connected between the positive electrode and a neutral-point voltage and between the neutral-point voltage and the negative electrode of the filtering and voltage-sharing circuit; the action of the double MOS tubes is controlled through the driving circuit and the PWM conversion circuit; when the double MOS tubes do not act synchronously, a double-side coil of the impulse voltage-stabilizing transformer generates induction voltages with the same potential and opposite polarities, so that the double MOS tubes are kept at half voltage, and a target voltage is output after the direct-current voltage is subjected to PWM modulation. AC-DC conversion of AC 50-500V voltage output by an underground three-phase generator is realized, and stable work is realized.

Description

technical field [0001] The present invention relates to the technical field of oilfield drilling wireless drilling system, in particular to a wide-range AC-DC power conversion system and method for drilling wireless drilling instrument. 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] During oilfield drilling, there are spectrum measurement and rotary steering systems in the wireless drilling system. These two systems must be powered by high-power power supplies, and this power supply can only be realized by using downhole generators. 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 ...

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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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