Schlumberger Technology Corporation

Yaoxin Qian

In Chul Jang

Mustafa Kamil Guven

Torgeir Rusten

John Parry

A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

Active alternator control in a downhole tool string

A fault tolerant inverter or controlled rectifier system includes a first leg having at least one switch device, a spare leg having at least one spare switch device, a spare leg connect switch associated with the spare leg and the first leg, a fault detection sub-system for detecting a fault in the first leg and outputting a signal on detection of a fault in the first leg, and a leg selection control sub-system that receives the signal output by the fault detection sub-system and controls the operation of the spare leg connect switch in accordance with the output signal, such that on detection of a fault the spare leg may be activated to take over the operation of the first leg.

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Missouri City, TX, United States of America

Yaoxin Qian