Design of Flux Observer Robust to Interior Permanent-Magnet Synchronous Motor Flux Variation

This paper presents a modified flux observer which is robust to the variation of the permanent-magnet flux linkage of an interior permanent-magnet synchronous motor (IPMSM). The IPMSM is driven by a current-regulated inverter, where the d-q axis currents are controlled by two proportional and integral controllers with feedforward cross-coupling decoupling terms. The integrator outputs of the current regulator reflecting flux errors are used to compensate the flux variation according to the operating temperature and manufacturing tolerance. The proposed flux observer shows satisfactory performance not only in maximum torque per ampere operating region but also in flux weakening region. The experimental results reveal the effectiveness of the proposed observer.