A novel sensorless IPM motor drive for electric submersible pumps

Electric submersible pumps (ESPs) are widely deployed for oil and gas production from deep downhole reservoirs. ESPs are located inside a well from hundreds to several thousands of feet below the surface. A variable speed drive (VSD) is situated on the surface platform, and power is supplied to the ESP from the VSD through long downhole cables that run down the well. Due to the long cable length, position sensor based speed controllers for traditional IPM drives are impractical for ESPs. In this paper, a novel sensorless controller is proposed for stable and efficient operation of IPM motor driven ESPs. The proposed controller applies a back-emf estimation algorithm to determine the rotor position. A novel sensorless V/f controller coupled with the back-emf estimation algorithm is designed to start and stabilize the IPM-ESP drive at a low speed. A new transition algorithm is developed to switch from sensorless V/f control state to vector control for improving efficiency and power factor. The developed sensorless control technique is investigated on a 3-phase, 6-pole, 575V, 10-HP submersible IPM-ESP drive system; and the performance results are presented in this paper.