Sensorless Control of CSC-Fed PMSM Drives With Low Switching Frequency for Electrical Submersible Pump Application

In this article, current source converter (CSC)-fed permanent magnet synchronous motor (PMSM) drives are investigated for electrical submersible pump (ESP) applications. The CSC features motor-friendly waveform with low dv/dt, which is very suitable for long cable application. High-speed ESP by adopting a PMSM has higher efficiency and shorter length and diameter compared with the counterpart adopting induction motor. Sensorless control instead of mechanical sensor can further reduce the system size/cost and improve reliability due to the harsh downhole environment. However, low switching frequency and an inverter-side output filter cause great challenge in controller and observer design. These kinds of influence become more serious under a higher speed region due to the limited updates per fundamental cycle. To overcome these challenges, the dynamic capacitor voltage control is employed in a field-oriented control scheme to enhance the system dynamic response. Moreover, a discrete-time sliding mode observer based rotor position estimation method is proposed to reduce estimation error and improve parameter uncertainty robustness. The effectiveness of the proposed method is verified on a CSC-fed PMSM with simulation and experimental results.