Computer intermittently loses power when unplugged.

Why do the equipment on a cart shut down when unit is unplugged from the wall as if they had pulled the plug on everything?�

Power for the inverter comes in waves. There is an upslope then a down slope. Energy moves from the computer to the inverter the same exact way. The reason the issue is intermittent is because the user is unplugging the cart on a downward slope of power. The inverter has a transfer switch. There is a 30 millisecond (power gap) delay from switching over from wall power to inverter power then running on the battery. When one unplugs from the wall and the computer shuts down, it is being unplugged during the downward slope and the computer is shutting down because there isn�t enough time for it to transfer the power and keep the computer on.