Distortion-Minimizing Flux Observer for IPMSM Based on Frequency-Adaptive Observers

For stable and efficient drives of interior permanent-magnet synchronous machines (IPMSMs), stator flux should be observed across a wide speed range. However, distortions such as a dc offset and low-order harmonics are contained in the estimated flux due to various reasons. In this paper, a distortion-minimizing flux observer is proposed to suppress the effects of dc offset and harmonics by implementing frequency-adaptive observers. The proposed frequency-adaptive flux observer is designed to extract a fundamental flux while keeping a simple structure even if the rotating speed of the IPMSM varies. The fundamental flux could be estimated by the proposed current- and voltage-model based flux observer, which is implemented with the frequency-adaptive observer and harmonic extractors. Moreover, parameter sensitivity and model transition are discussed to improve the performance of the proposed observers. The validity and effectiveness of the proposed methods are verified with simulation and experimental results.