This paper presents a test bench developed to characterize modular power converters. It is composed by a thermally isolated wind tunnel in which the temperature and the air flow can be measured and regulated. A device under test is placed inside and all the important signals are acquired and processed. Large and multi-dimension experimental plans can be automated thanks to computer interface allowing a fast way to sketch converter abacus and characteristics. The bench is especially suitable to characterize PCB based and directly air cooled individual blocks of modular converters as well as matrices of modular converters.