A dual-input nine-phase autotransformer converts first and second three-phase AC inputs to a nine-phase AC output. The autotransformer includes input terminals for connection to a first three-phase AC input and a second three-phase AC input smaller than the first three-phase AC input. The autotransformer includes a first plurality of coils, a second plurality, and a third plurality of coils wound on respective phase legs of the autotransformer. The autotransformer includes a plurality of output terminals for providing a plurality of AC output voltages, and a plurality of internal terminals for connecting the first, second, and third plurality of coils in a configuration that provides a 40° phase shift in the AC outputs provided by the dual-input nine-phase autotransformer.