The invention relates to a method for estimating a temperature contribution of an inverter used to energize an electrical machine, in particular a synchronous machine. The method comprises the steps for calculating oscillating temperature swings of components of the inverter; and determining, as the estimated temperature contribution ([delta]T(omega), [delta]Ti(omega), [delta]Td(omega)) of the inverter, an upper envelope of an amplitude of a sum of the calculated oscillating temperature swings. The method according to the invention or an apparatus designed to carry out the method can be expanded for the purpose of estimating a temperature or a complete temperature contribution of the inverter and is provided, in particular, for use in an electric vehicle or a hybrid vehicle having an electrical drive without a variable speed gear in order to estimate the operating temperature of vehicle drive power electronics accommodated therein.