Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

In this article, we propose a new scheme to use active flux on the q -axis for sensorless control of synchronous reluctance machines (SynRMs). Conventionally, "active flux" on the d -axis is adopted to convert a salient-pole machine into a fictitious nonsalient-pole machine. However, the injected d -axis flux can deteriorate high-frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This article demonstrates that active flux on the q -axis can support back EMF sensorless control at high speed and improve low-speed HFI performance substantially. A seamless transition from HFI sensorless method to back EMF voltage method is attained after adopting the proposed active q flux. The experimental results are used to validate the proposed method.