Power management apparatuses and systems utilizing synchronous common coupling. A power management apparatus may include a plurality of ports and a plurality of electrically isolated stacks connected through a synchronous common coupling. Each electrically isolated stack may include a plurality of cascaded stages and may be connected to a source or load through one of the plurality of ports. The synchronous common coupling connects only power between each of the plurality of electrically isolated stacks and is configured to maintain electrical isolation for each of the plurality of stages in the plurality of electrically isolated stacks.