If Ashe picks the Silver Lighter Perk (Ability Rare) she can gain ult charge by damaging herself. I was just messing around in areas where you can damage yourself during armory phase and I was able to gain ult charge by letting dynamite damage me, does not seem to occur without the item.
In the same vein I wonder if it’s possible to use Soldier’s stim pack to self-damage in spawn to generate healing ult charge for self or allies.