Study on a new nonlinear perpendicular flux observer with feedback compensation for DTC application

A new flux observer suitable for DTC application is presented in this paper, which is capable of ensuring flux linkage to be perpendicular to back electromotive force, so that the stator flux linkage can be estimated accurately over a wide speed range. Therefore the proposed observer could solve those problems associated with conventional observer such as DC drift, magnetic saturation and inaccurate estimation of stator flux linkage at very low speed operation. The feasibility and correctness were verified by the DTC controller in a 2 kW PMSM setup via a digital signal processor (DSP). Experiment results indicate that the proposed observer is capable of estimating accurately the stator flux linkage including its amplitude and phase angle when motor runs at a very low frequency of 0.7 Hz and at the rated frequency of 100 Hz. The high performance operation for PMSM DTC using proposed flux observer has been achieved with satisfaction in laboratory