Saturation measurements in AC machines using carrier signal injection

This paper presents a technique for measuring the position and magnitude of saliencies in AC machines by injecting a balanced, three-phase, carrier signal. The technique allows detection of where a machine saturates under a full range operating conditions, without any modification to the machine design or construction. From these measurements insight into the causes of saturation and suggestions for improvement in the machine design can be obtained. Experimental results on an induction machine show that saturation-induced saliencies can he significant at allow levels and are not fixed in position relative to any component of flux. Detailed analysis and discussion of the experimental results are included.