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. And conventional high-frequency signal injection sensorless methods are based on physical magnetic saliency. Therefore, conventional methods cannot be applied to the SMIIR which has no sufficient magnetic saliency. The proposed sensorless method suggests virtual resistance saliency created by the rotor-side inverter, whose axes can be placed arbitrarily. Based on this virtual saliency the rotor position information is included and excluded in the relationship between the high-frequency stator voltage and stator current. Because the SMIIR already injects high-frequency voltage for the power transfer, there is no need to inject additional voltage for the proposed high-frequency sensorless method. And initial +d axis detection algorithm using the rotor-side inverter without using magnetic saturation is also proposed. The feasibility of the proposed sensorless method was verified by experimental results with the prototype SMIIR.