Performance of a new commutation approach for switched reluctance generators

Switched reluctance generators have been identified as a potential option for military aircraft electric power systems. Two areas of desired improvement are: an improved approach for production of significant DC link current at reduced bus voltage for fault clearing; and a reduction in generator output current ripple resulting in smaller DC bus filtering. The present approach for improving the low voltage output characteristics of a switched reluctance generator has the penalty of increased system size and weight. Conventional commutation approaches for switched reluctance generators are limited in their ability to reduce DC current ripple. A new method of commutating the switched reluctance generator has been developed that has demonstrated, both analytically and in the laboratory, significant improvement in the ability of a 30 kW, 270 VDC switched reluctance generator to deliver rated current with a bus voltage of approximately 50 volts without a separate excitation source. It has also been shown analytically that the new commutation approach reduces the ripple current at the output of the inverter, resulting in lower bus voltage ripple for a given output filter. Analysis and testing are continuing to explore further the low voltage operation, current ripple characteristics and machine efficiency with the new commutation approach.