Sensorless control of a PMSM with a transmission system including shunt branches

In oil and gas applications, permanent magnet synchronous motors (PMSM) are becoming a preferred choice to drive subsea and submersible pumps to achieve higher efficiency than induction motors. In the drive system, a submersible PMSM is fed through a transmission system by a top-side variable speed drive. Previous studies have included the series impedance of the transmission system but excluded the transformer magnetizing branch and the cable capacitive branches. In this work, both the series impedance and the shunt admittance of the transmission system are considered. The PMSM current controller is restructured to be an inverter current controller. A static estimator is implemented to estimate the PMSM stator voltage and current. Sensorless control is realized by combining the statically compensated voltage model method and the high frequency injection method. The developed controller can successfully start and accelerate the PMSM from standing still up to 6000 rev/min within 5 s