Estimation of Field Current in Synchronous Generators with Brushless Synchronous Exciter

Measurement of field current or voltage is of primary importance to the synchronous machines, in order to control and identification purposes. In brushless synchronous generators employing synchronous exciter, direct measurement of field current is normally not possible, since the exciter armature winding and the rectifier are rotating and not accessible. This paper presents two methods for field current and voltage estimation in brushless generators utilizing synchronous exciter. The estimation methods are verified through comparison of the estimation results and the experimental results performed on a laboratory synchronous generator