To provide a compact forced air cooling power converter with enhanced reliability by locating a cooling body of a variable speed control section in a wind tunnel and cooling it with cooling wind from a fan thereby eliminating the fan for the variable speed control section.

Body section 6 of a power converter is provided in a wind tunnel 5a, fans 9 and 10 are provided out of the wind tunnel 5a in the body section 5b within a package 5, no fan is provided in variable speed control sections 11 and 12 controlling the fans 9 and 10, and their cooling bodies 13 and 14 are located in the wind tunnel 5a and cooled with cooling wind from the fans 9 and 10.