Discrete-time SMO based Sensorless Control of CSC-fed PMSM Drives with Low Switching Frequency

In this paper, 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 PMSM has higher efficiency, shorter length and diameter compared with the counterpart which adopting induction motor (IM). Sensorless control instead of mechanical sensor can further reduce the system size/cost and improve reliability. However, low switching frequency and inverter-side output filter cause great challenge in controller and observer design. These kinds of influence become more serious under higher speed region due to the limited updates per fundamental cycle. To overcome these challenges, the dynamic capacitor voltage control (DVC) is employed in field-oriented control (FOC) scheme to enhance the system dynamic response. Moreover, a discrete-time sliding mode observer (SMO) 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 permanent synchronous machine (PMSM) with simulation and experiment results.