| 摘要 |
A downhole compressor system is disclosed for assisting in extracting gas from the well. The system comprises a compressor 14 , an electric motor 10 for driving the compressor 14 which motor has a stator winding and a rotor 12 and, in use, is lowered into the well together with the compressor. A control system 18 , which when in use is disposed outside the well, is connected to the stator winding for controlling the current supply to the motor 10 . The control system 18 receiving a signal indicative of the speed and phase of the rotor from a feedback sensor 16 mounted for rotation with the rotor 12 . In the invention, the feedback sensor is a current generator having a permanent magnet 16 a mounted for rotation with the rotor 12 and a second stator winding 16 b connected to the control system 18.
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