Motor? As in elecric motor?
why would you use electricity to generate less electricity?
3 phase alternators are easily paralleled. They are also generally large that enough one would run several homes so there's no need to parallel them.
Automobile alternators provide DC so were your home wired for it and all appliances DC , you might run such alternators from an internal combustion engine and parallel them.
The 3 phase AC that they internally rectify into DC is at frequencies unuseable by most appliances so that is not practical. And you'll incur more fuel cost than you save on your electric bill .
If this is a suvivalist undertaking - go ahead with a DC system it'll work.
If it's a perpetual motion undertaking it's a violation of both Physics Forum's rules and Nature's Laws, so with all due respect take it someplace else .
But keep up your curiosity, and do more research.
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