An Effective Encoderless Control for PMSM Drives: an Enhanced Active Flux Observation Technique

Permanent magnet synchronous motor drives with encoderless control techniques will simplify servo system de-sign, reduce cost, and improve reliability, which has therefore attracted decades of research in both the areas of academia and industry. Owing to its simple structure and reduced application requirements, model-based encoderless control methods have been widely used. Active flux model based technique shows good robustness thanks to its low parameter dependence. However, inverter non-linearity, dead time, and IGBT voltage drop will in-evitably cause mismatches between the desired and actual voltage outputs, which considerably affects the active flux estimation, and hence deteriorates the encoderless control performance. In this work, we propose a simple extended state observer based method to accurately estimate the active flux. Experiments confirm that the proposed technique achieves both good steady and dynamic performances at a wide speed range.