Graphical Method for Cross-Coupling Effect Online Suppression in Sensorless Predictive Direct Torque Controlled IPMSM Drives

The cross-coupling effect is the magnetic coupling effect of the flux caused by direct-axis current and quadrature-axis current due to nonlinear characteristics of core material. The knowledge of the cross-coupling inductance is of particular importance in order to obtain the angle deviation of magnetic axis from geometric axis of the rotor lamination, which will contribute to the minimization of rotor position estimation error. However, the cross-coupling inductance varies with operating conditions and is often ignored in rotor position estimator. This article proposes a general online method for sensorless predictive direct torque control identifying angle deviation of magnetic axis from geometric axis caused by the cross-coupling effect. Only intrinsic electrical signals for machine drives are employed to build response points distribution graph and implement the angle deviation identification. Experimental results verify that the proposed graphical method online identifies the angle deviation and effectively suppresses the estimation error in the rotor position estimator caused by the cross-coupling effect.