As far as I know, the only countries where you are obliged to carry your ID are Portugal and the Netherlands. In Germany you are required to possess one but not to carry it with you, except in special cases (fields of work known for a high percantage of illegal workers, people carrying weapons, police men). If you do not posses a valid ID, you will be fined up to 3000€. But do note that you are required to identify yourself to the police or other official institutions and if you are unable to they might escort you home to present your id or to the police office to identify you there.

Bulgarian here. The punishment for not having an ID when a police officer requests it, is being jailed until someone with an ID can come and ID you.