Online Estimation of VSI Nonlinearity in PMSM Based on Third-Order Generalized Integrator

Voltage-source-inverter (VSI) nonlinearity causes current distortion and degrades the accuracy of parameter identification and sensorless control in permanent magnet synchronous machine (PMSM) drives. This letter proposes a novel online estimation method for VSI nonlinearity voltage based on third-order generalized integrators (TOGIs). The impacts of limited current control bandwidth and phase misalignment on estimation accuracy are systematically investigated for the first time. To address these issues, the proposed method employs TOGIs to extract the sixth-order harmonic amplitudes from both thed-axis reference voltageud,refand the dead-time coefficientDd, and easily estimates the nonlinearity voltage through their ratio, thereby enabling more accurate estimation by effectively eliminating errors induced by limited current control bandwidth and phase misalignment. Experimental results validate the effectiveness and superiority of the proposed method.