Adaptive Sensorless Control of High Speed Surface-Mounted PMSM Drives with Inductance Estimator based on Current Error

Due to their high power density, high efficiency and wide speed range, high speed surface-mounted permanent magnet synchronous motors (SPMSMs) with model-based sensorless field-oriented control (FOC) are evolving rapidly. The accuracy of conventional sensorless control method for SPMSM based on d-axis current error mainly relies on estimated inductance. However, the actual inductance varies in a wide range with different loads, which greatly degrades the performance and narrows the application scope. Therefore, this paper proposes an inductance estimator, which utilizes both daxis and q-axis current errors to construct a second-order inductance error equation. Consequently, the inductance can be estimated in an adaptive manner to improve the sensorless accuracy in various working conditions. The proposed inductance estimation method is validated on a 14krpm SPMSM, showing convergence from estimated to actual inductances at different loads even with +/- 50% inductance variation. As a result, the current amplitude is reduced by more than 10% at full load, verifying the high accuracy and effectiveness of the proposed method.