A modified sensorless method for PMSM drive with small DC-link capacitor

This paper has focused on the modified sensorless method for PMSM drive, which could estimate the rotor position information with the small DC-link capacitor. Due to the evaporation of electrolyte with working time, the electrolytic capacitor is vulnerable to the current ripple and heat. Thus, the film capacitor is selected as the DC-link capacitor in recent years. However, the capacitance of film capacitor is quite small compared with electrolytic capacitor. Moreover, the DC-link voltage would vary with three-phase currents, which would bring errors on rotor position estimation. The proposed modified sensorless method based on Matsui's method is able to remove the influence of small DC-link capacitor on position estimation by additional synchronous filters on d and q axis. Furthermore, the proposed method neither employs the additional circuits in the drive nor changes the design of the standard vector control loops. At last the effectiveness of proposed strategy is verified by computer simulations.