A rotary power converter apparatus for coupling power between a prime driver and plural generators. The apparatus includes a frame having a first and second bearing aligned along an axis of rotation and a rotor assembly supported thereby. The rotor assembly includes a shaft fabricated from a light weight material that is rotatably supported along the axis of rotation by the first and second bearings. There is a prime-driver rotor assembly, that has a magnetic structure supported by a light weight non-magnetic alloy hub that is fixed to rotate with the shaft. There are also plural generator rotor assemblies, each having a permanent magnet structure supported by a light weight non magnetic alloy hub also fixed to rotate with the shaft. A prime driver stator assembly is fixedly supported by the frame and aligned concentric with the prime driver rotor assembly to enable magnetic coupling of power therewith. There are also plural generator stator assemblies fixedly supported by the frame, and each aligned concentric with one of the plural generator rotor assemblies to enable magnetic coupling of power therewith.