LUT-Less Sensorless Control of Synchronous Reluctance Machines Using the Locus of Incremental Saliency Ratio Tracking (LIST)

This article deals with the lookup table (LUT) less sensorless control of synchronous reluctance (SyR) machines at zero and low speeds, where LUT-less stands for avoiding the use of flux-map LUTs or other predetermined machine parameters. The new signal-injection-based control scheme called the locus of incremental saliency ratio tracking is presented, where a pulsating high-frequency voltage component is used for position tracking and a second rotating signal-injection is dedicated to online estimating the incremental saliency ratio. A trajectory of constant incremental saliency ratio is used for torque regulation, resulting in stable control at all operating conditions, including overload. This despite the effect of cross-saturation, which is known to introduce position error and harm the control stability progressively with the load. The proposed scheme is validated experimentally on a 1.1-kW SyR machine test bench. Alternative LUT-less torque control laws are investigated, and their stability limits put in evidence using convergence analysis and experiments.