부산대학교 도서관

Virtual current sensors (VCSs) are promising solutions for accurate current measurement in high performance and low cost permanent magnet synchronous machine (PMSM) drives. They not only help identify faults in hardware current sensors, but also ensure the continuous operation of PMSM drive system with reduced hardware current sensor counts. However, traditional observer based VCSs have limitations in terms of slow response and large overshoot, which could lead to detection errors in condition monitoring of hardware current sensors and degraded control performance when VSCs are employed in the control loop. This article proposes an enhanced nonlinear observer based VCSs approach for PMSM drives. A novel nonlinear function with a smooth inflection point is introduced to design the nonlinear observer. This nonlinear function enables an adaptive observer gain update corresponding to the current error, which contributes to a varied damping ratio in the current observer for improved dynamics. As a result, the proposed enhanced nonlinear observer (ENO) based VCSs approach achieves fast response with small current overshoot. The proposed ENO based VCSs are validated with both simulation and experimental test results on a laboratory interior PMSM drive in different VCS application scenarios.