Sensorless control of synchronous motor drives: Accurate torque estimation and control under parameter errors

Accurate torque control is of interest in traction and other industrial applications, whose realization is challenged by parameters errors and temperature-induced variations. This article proposes a sensorless technique for resilient torque control in salient synchronous machines. The position observer is driven by the adaptive projection vector for the position error estimation (APP) scheme. A second projection vector, orthogonal to APP for noninterference, serves for flux adaptation. Based on the torque estimation, a model-based optimal current reference generation for maximum torque per ampere (MTPA) condition is designed to realize accurate torque control. The proposed scheme is validated experimentally on a 1.1-kW synchronous reluctance (SyR) machine test bench.