Research on TOGI-EFLL flux observer for IPMSM sensorless control

For the purpose of enhancing the performance of interior permanent magnet synchronous motors (IPMSMs) sensorless control, a flux observer based on a third-order generalized integrator with enhanced frequency-locked loop (TOGI-EFLL) is introduced in this paper. Compared with the traditional second-order generalized integrator with frequency-locked loop (SOGI-FLL), the proposed TOGI-EFLL can effectively mitigate the direct current (DC) bias stemming from non-ideal factors, such as the inverter non-linearities and detection errors, without introducing additional parameters. Initially, the active flux observer model and the limitations of the conventional SOGI-FLL are presented. Subsequently, the proposed flux observer based on TOGI-EFLL has been intensively investigated. Furthermore, the design of the damping factor and the digital implementation of the algorithm are developed to ensure seamless integration into digital systems. Finally, the effectiveness of the proposed sensorless control strategy is validated through the comprehensive experimental results.