Parameter Estimation for Sensorless Position Control of PMSM Drives with Long Cable in Subsea Applications

There is an increasing interest in powering the subsea loads, such as subsea motor drives, from the renewable energy sources either from the shore or from offshore. Due to the long distance from the motor controller to the motor, the use of sensor cables lead to EMI and noise problems in the position information signals. Hence, sensorless operation of subsea drives becomes very important. Also, variation in the system parameters due to changes in operating conditions can result in the deterioration of the performance of drives and may even lead to unstable operation. A closed-loop observer-based method is used to estimate the speed and inductance of the equivalent system, which includes a transformer, cable, and motor inductances. The proposed scheme is validated using MATLAB simulation and Typhoon hardware-in-the-loop for a 500kW, 4.2kV Interior Permanent Magnet Synchronous Motor (IPMSM).