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

For stable and efficient operation of IPMSM, the stator flux should be observed across a wide speed range including low-speed. However, not only a de offset but also 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 dc offset and harmonic flux errors by adopting frequency-adaptive observers. A frequency-adaptive observer is appropriate to extract the fundamental component while keeping a simple structure even if a rotating speed of IPMSM varies. The fundamental flux could be estimated quickly by the proposed current- and voltage- model based flux observer, which is implemented with not only the frequency-adaptive observer but also harmonic extractors. Robustness and effectiveness of the proposed methods are verified with simulation and experimental results. Through the proposed algorithms, the fundamental stator flux can be estimated while maintaining high dynamic performance over a wide speed range.