My spaceship includes a technology that creates artificial gravity (AG). For all intents and purposes the inner workings of the device are unknown. It's essentially a black box. What is understood is that the device exponentially increases the gravitational pull of matter inside it when it is fed power. Gravity can be increased to earth gravity or near neutron star levels, which allows for warp travel. The problem is that doing that would kill everyone in the process and crush the ship into a pebble. It needs a way to be cancelled or else it won't be much use.
I checked this question and it gave me an idea. Gravity is additive and can't be negative. However if two sources pull in opposite directions it should cancel itself out. So after a bit of brainstorming a ring would be the best option. Gravity is multidirectional, so the gravity emanating from a ring would pull things outside but gravity inside the ring should be neutral.
Theoretically, would this gravity donut design work? What else (aside from how the AG works) would need to be taken into account?
Be constructive please.