Self excitation of iron core homopolar generators

In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at The University of Texas at Austin (CEM-UT). In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A seven-turn field coil, having a nominal resistance of 500 µΩ was fabricated for the CEM-UT compact HPG system tester and subsequently tested. At 6,000 rpm, a field current rise time of 1 s was achieved and resulted in an average peak field density of 1.94 T. Only 300 kJ, about 13% of the 2.27 MJ stored in the rotor was required to fully excite the generator.