In addition to my escort idea separately posted, here is a way to allow carriers to defend themselves in PVP Play.
Add an additional fighter wing to carriers/super carriers, named Combat Air Patrol.
If this fighter wing is launched it will orbit the carrier automatically. It cannot be sent to attack.
If the Combat Air Patrol has been launched, and the carrier is fired on by nonfleet drones or fighters, the Combat Air Patrol will automatically begin attacking the offending drones/fighters.
OPTION - Alternatively (as in the carrier pilot can fit one or the other) or additionally (the pilot can fit both), a carrier can be given a Torpedo Bomber FIghter Squadron which can only be used to attack enemy capital ships. If possible, make it so its not useful in PVE.
This would give a carrier some additional firepower and defensive ability in a fleet action, making their use in fleets more likely.