Inverter protected in respect of the rates of increase of current and voltage

DETAILED DESCRIPTION The object of the present invention is to provide an inverter in which the energies of the di/dt protective choke and of the du/dt protective capacitor are not dissipated as heat, but they are returned to the filter capacitor of the DC-voltage side of the inverter, so that the efficiency of the arrangement is improved remarkably.
According to the invention, this has been accomplished so that the members protecting with respect to the voltage increase rate comprise, for each phase, a series connection of a capacitor and a diode connected in parallel with only one of the controlled semiconductor switches and that the energy transfer means comprises a diode connected between the connection point between the series connected protective capacitor and diode, and the other terminal of the energy transfer diode is and one a terminal of a storage capacitor.
In the case of a three-phase inverter, the inverter is characterized in that the means for transferring energy to a storage capacitor common for all phases comprises diodes connected between the connection points between the series connected protective capacitor and diode for each phase, and the terminal of the storage capacitor.