Rangelov, capped 24 times, moved to Dortmund from German rivals Energie Cottbus in 2009 but struggled to win a regular first-team place.
Luzern said the 29-year-old, who has also played for Slavia Sofia, Strasbourg and Maccabi Tel Aviv, had an option for a third year.
The Swiss club will compete in the Europa League play-off round in August.

Reuters












