National Oilwell Varco, L.p.

Shanghai Sim-bcd Semiconductor Manufacturing Co., Ltd.

Lei Cheng

Robert B Donnally

Andrew Ian McKenzie

Qun Li

Zhimin Hu

Junelei Li

Leo Yang

George Wu

A lubricator assembly for servicing a tubular member includes a mounting base, a lubricant housing movably coupled to the mounting base and configured to receive lubricant from a lubricant source, a guide pin slidably disposed in the lubricant housing, a first seal positioned between the guide pin and the lubricant housing and a second seal positioned between the guide pin and the lubricant housing, and a first chamber extending between the first seal and the second seal, wherein the guide pin is configured to direct lubricant disposed in the first chamber against the tubular member in response to the tubular member engaging the guide pin.

Lubricator assembly and method for servicing tubular members

A switch mode power supply (SMPS) includes a buck converter circuit that includes a first inductor coupled to an output terminal and a switch device coupled the first inductor. A controller is configured for regulating the output current based at least in part on controlling a peak current in the first inductor according to a ratio between an instantaneous voltage to an average voltage at the negative output terminal. The controller is configured to cause the SMPS to operate in a boundary conduction mode (BCM). The controller is configured to maintain a constant average output current that is substantially independent of the input voltage and the output voltage, and also provide a high power factor.

Method and circuit for constant current buck converter

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Shanghai, China

Lei Cheng