Enhancement of parameter estimation accuracy using current shaping in PM machine drive

Abstract

The accurate value of the electric machine parameters is required to design an efficient current controller and torque controller in the permanent magnet synchronous machine (PMSM) drive system. The values of these parameters are not constant but vary with the operation condition. The stator winding resistance and rotor flux linkage are affected by the temperature. Inductances are changed according to the magnetic saturation. So each parameter need to be estimated in real time and updated to each controller. This paper enhances the accuracy of on-line parameter estimation in the low speed operation region using the proposed current shaping method. In the low speed operation region, the nonlinearity of voltage source inverter (VSI) causes estimation error. The proposed method adjusts the current reference to change rapidly at zero current region because the nonlinearity is severe at the region. By the dead time compensation and the proposed current shaping, the error caused area is reduced and estimation accuracy can be increased. Experimental results prove the feasibility and effectiveness of the proposed method.