Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

This paper proposes a new scheme to use active flux on q-axis for sensorless control of synchronous reluctance machines (SynRM). Conventionally, “Active Flux” on d-axis is adopted to convert a salient pole machine into a fictitious non-salient 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 paper demonstrates active flux on 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. Experiment results are used to validate the proposed method.