Problem of cryogenic cooling of semiconductor switches for power convertors

Currently, in Russia and abroad there is a significant progress in the development and manufacturing of electromechanical devices based on high-temperature superconducting materials. These devices possess the specific power at liquid nitrogen cooling above 10 kW/kg. Semiconductor convertors, which normally are necessary to operate together with electromechanical converters, have the specific power not exceeding 1 kW/kg at forced cooling. Therefore, the problem of increasing of the specific power of both electromechanical and static electrical devices of mobile objects (especially at operating in the aerospace field) is very relevant. The paper is devoted to the cooling of semiconductor electronic switches for semiconductor power converters at liquid nitrogen environment. In this case the improvement of cooling efficiency leads to a significant increase of the heat-transfer factor and, as a consequence, decreasing the mass and size of the radiators, and total weight and size of the semiconductor converters. The calculations which were carried out according to the results of the experiments showed that the use of cryogenic cooling allows increasing about ~100 times the specific power of the semiconductor converters. The researches have shown that the placement of semiconductor converter in the medium of liquid nitrogen is most perspective for real application