Position and velocity sensorless control of IPMSM using full-order observer based on extended electromotive force with a new observer design method

The reduced order observer (disturbance observer) based on the the extended electromotive force(eemf) model, which can be applied to the position and velocity sensorless control for all synchronous motors included IPMSMs(Interior Permanent Magnet Synchronous Motors), had been proposed by authors. However, the design of a full-order eemf observer is difficult, because the error equations of the observers become ones of the fourth order. Therefore, this paper proposes a design method of the full-order eemf observer whose objective is the robust position estimation against the velocity estimation error, using H_∞ control theory. Moreover, a new design method of the more robust full-order eemf observer is proposed by restudying the error system of the observer, and the simulation and experimental results of the position and velocity sensorless control of IPMSM under the maximum torque per ampere(MTPA) show that a new design method of the full-order eemf observer is very useful.