An electrical power converter for a working machine

An electrical power converter comprises a capacitive intermediate circuit (101) and a converter-stage (102) for converting direct voltage between first and second poles of the intermediate circuit into output voltage. The intermediate circuit comprises a first capacitive element (103) connected to the first and second poles, a second capacitive element (104) connected to the second pole and having greater capacitance but lower maximum allowable voltage than the first capacitive element, and a controllable switch (105) connected to the second capacitive element and to the first pole. The controllable switch is conductive in order to utilize the energy storage capacity of the second capacitive element when the direct voltage does not need to be higher than the maximum allowable voltage of the second capacitive element. In other cases, the controllable switch is non-conductive in order to allow the direct voltage to be higher than the above-mentioned maximum allowable voltage.