Initial rotor position identification in medium voltage synchronous machines

Electrically excited synchronous machines (SM) are a machine type commonly used in high power variable speed drives. For the realization of a high performance control scheme the knowledge of the actual rotor or flux position is mandatory and can be obtained by using a sensor attached to the shaft. To overcome the dependency on an encoder this information is obtained by adequate machine models which work reliably above a certain speed level. Yet, the encoderless identification of the initial rotor position is more challenging. In the following, a new identification method is presented which permits the detection of the rotor position of the SM at standstill with a special focus on brushless excited SMs. Experimental results demonstrate the reliability of this method.