Analysis of the temperature conditions of semiconductor power switches is an obligatory stage in design of converters of electric energy parameters. When constructing a high performance converter with a high specific power, the following procedures of development of cooling systems for a given converter are necessary: optimization of radiator profiles, calculation of optimal switching frequencies of power switches. The current paper contains a calculation of static and switching losses of power in power switches of a three-phase matrix frequency converter, and analysis of temperature conditions of power switches performed analytically and by means of finite element method using the Ansys Icepak program. The results of the research were used in development of a prototype of a bilateral power key of a matrix frequency converter and were confirmed experimentally.