The invention relates to a method for preheating of power semiconductors. The power semiconductors are arranged in converters, in particular at a DC voltage intermediate circuit, wherein a temperature of at least one of the power semiconductors is measured by means of a temperature detector. A comparison of the temperature of the at least one power semiconductors with a reference temperature is perforamed and a result of the comparison is provided. A pre-heating phase for preheating the power semiconductors as a function of the result is activated; during the pre-heating phase, a pre-heating current is defined; and the pre-heating current is input into an electrical load, especially into an electric machine. Furthermore, a computing unit for performing the method is provided as well as a driving device which is designed to execute the process with the computing unit. Also provided are the converters in the DC voltage intermediate circuit, comprising the power semiconductor, the computing unit and the driving device; and an electric or hybrid vehicle having an electric machine able to be driven by the converter, in particular an asynchronous machine or a synchronous machine.