Determination of the inductances and the rotor flux-linkage of a permanent-field synchronous machine with reluctance effects

The knowledge of the real machine parameters is necessary for the calculation of the operating behavior, for the determination of the control circuit parameters when the machine is part of a control loop and last but not least for the verification of the predicted values obtained in the design phase of the machine. The known procedures for the measurement of the direct-axis inductance and the quadrature-axis inductance of salient-pole synchronous machines cannot be applied to permanent-field synchronous machines because these procedures require a vanishing rotor field. The objective of our work was the experimental determination of the relevant real machine parameters. This means that also saturation effects on these machine parameters must be detected. The implementation of the method into appropriate measuring stations results in a very effective means for experimental machine investigations. The paper describes the theoretical background of the applied parameter identification and discusses two different measuring and analysis systems.