| 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 16a mounted for rotation with the rotor 12 and a second stator winding 16b connected to the control system 18. <IMAGE> <IMAGE>
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