Improved MOGIFO-Based Flux Observation Strategy for PMSM Sensorless Drives

Due to parameter variations, measurement errors, and converter non-linearities of for permanent magnet synchronous machine (PMSM) system, traditional rotor flux observers suffer from the dc drift and harmonics. Benefit from the filter characteristics, the generalized integrators are applied to reduce the harmonics and dc offset. Nevertheless, the dc component in estimated rotor flux cannot be removed effectively by second-order generalized integrator. In this work, by combining the second- and third order generalized integrators, a mixed-order generalized integral flux observer (MOGIFO) is designed. With enhanced filtering ability, it is theoretically proofed that the dc offset can be removed by the proposed MOGIFO. Based on the estimated rotor flux, the accurate rotor position and velocity can be extracted for sensorless drives. Finally, MOGIFO-based sensorless drive strategy for PMSM system are tested by the simulations and experimental results.