Accurate Initial Rotor Position Estimation of SPMSM Based on DC-Link Voltage Dip Analysis

This article proposes an initial rotor position estimation scheme for a surface-mounted permanent magnet synchronous motor. The proposed method involves injecting voltage in six 60° partitions sequentially to induce voltage dips across the dc-link capacitor. The maximum voltage dips during each voltage injection at 0° to 360° electrical rotor position are analyzed. The normalization is used to mitigate the effect of capacitor aging. The acquired data are curve-fitted to obtain six sets of two parabolic equations, which are finally used for the estimation process. The accuracy of the proposed method is verified through simulation and experiment by estimating the full initial electrical rotor position range. It showcases accurate estimation capability while using only one voltage sensor. Regardless of the parameter change or voltage pulse magnitude change, the maximum absolute estimation error is analyzed to be 0.4° and 1.37° in the simulations and experiments, respectively.