Abstract: A planetary gear system for setting a drive ratio of a transmission includes an outer ring gear; a plurality of planetary gears; an inner sun gear; a first rotary input coupled to one of the outer ring gear, the plurality of planetary gears, and the inner sun gear; a second rotary input coupled to another one of the outer ring gear, the plurality of planetary gears, and the inner sun gear; and a rotary output coupled to a remaining one of the outer ring gear, the plurality of planetary gears the inner sun gear. In some cases, the planetary gear system is combined with a second planetary gear system, and the first rotary input of the planetary gear system and the first rotary input of the second planetary gear system are the same, allowing generation of two independent outputs from three inputs.