Sensorless Control of Synchronous Machine With an Inverter Integrated Rotor

This paper proposes a new sensorless method for a synchronous machine with an inverter integrated rotor (SMIIR). The SMIIR is a newly developed machine based on the wound rotor synchronous machine (WRSM) but has no brushes and slip-rings. The conventional high-frequency signal injection sensorless methods are based on a physical magnetic saliency. Therefore, the conventional methods cannot be applied to the SMIIR since it has no adequate physical magnetic saliency. The proposed sensorless method suggests a virtual resistance saliency created by the rotor-side inverter, of which the saliency ratio and axes can be arbitrarily set. Based on this virtual saliency, the rotor position information can be included in the relationship between the high-frequency stator voltage and stator current independent of the machine parameters or operating conditions. Because the SMIIR inherently injects a high-frequency voltage for the power transfer, there is no need to inject additional voltage for the proposed high-frequency sensorless control. The initial d-axis detection algorithm using the rotor-side inverter without magnetic saturation is also proposed. The feasibility of the proposed sensorless method was verified by the experimental results of the prototype SMIIR.