Discrete-Time SMO Sensorless Control of Current Source Converter-Fed PMSM Drives With Low Switching Frequency

In this article, a sensorless control method for medium- and high-speed operation is proposed for a current source converter (CSC)-fed permanent magnet synchronous machine (PMSM) with low switching frequency. The low switching frequency as well as inverter-side capacitor filter can cause great challenges in controller and rotor speed/position observer design, especially under higher speed operation due to the limited updates per fundamental cycle and approaching to the LC resonant point. To improve the system dynamic performance and attenuate the LC resonant, a multi-loop controller with capacitor voltage control was added into conventional field-oriented control. Moreover, an exact discrete-time sliding mode observer based sensorless strategy with adaptive filter is proposed to improve the rotor speed and position estimation accuracy as well as robustness to system uncertainty. The effectiveness of the proposed method is verified on a transformerless CSC-fed PMSM drives with both simulation and experiment.