THE NOVEL WOUND-ROTOR HYBRID STEPPING MOTOR
|Jonathan U. Agber
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Hybrid stepping motors can be analyzed as synchronous motors with constant field excitation. One limitation on the operation of these motors is the inability to regulate the permanent magnet (PM) mmf in order to obtain a family of steady state characteristics like conventional synchronous motors. The aim of this paper is to investigate the dependence of the PM hybrid motor characteristics on rotor excitation. Hence the design and construction of a wound-rotor motor, in which the two permanent magnets in the rotor of the hybrid stepping motor were replaced with wound soft iron formers. Static tests with varying rotor mmf were carried out and the results obtained show that the holding torque varies with rotor excitation and also that the PM mmf varies with the stator excitation.