Modular Design for Sensorless Control of Synchronous Machine Drives With an LC Filter

This paper presents a modular design for sensorless control of synchronous machine drives equipped with an LC filter. The modularity allows for incorporating active damping into the existing flux-vector control law without redesigning the controller. A dedicated LC filter state observer is developed that interfaces with existing machine observer designs, enabling the reuse of established observer designs while addressing the challenges introduced by the LC filter. Small-signal analysis is used to obtain appropriate observer gains, ensuring that converter and stator current errors remain in the same direction. Both simulation and experimental results validate the proposed control.