An electric power converter device comprising: - at least one power electronics unit being electrically connected to an electric power input and an electric power output, - at least one fluid chamber being fluidically connected to a fluid inlet and a fluid outlet, - wherein the fluid chamber and the power electronics unit are thermally coupled such that waste heat generated by the power electronics unit is used for heating a fluid flowing through the fluid chamber, - wherein the electric power converter device has a first operation mode and a second operation mode, - wherein the amount of waste heat generated by the power electronics unit is increased in the second operation mode compared to the first operation mode, characterized in that it comprises: - at least one heating unit being electrically connected to an electric power input and electric power output, - the fluid chamber and the heating unit being thermally coupled, - wherein the heating unit is used to heat a fluid flowing through the fluid chamber, - wherein electric power converter device comprises a first housing and a second housing, - wherein the first housing and the second housing are separated by a fluid-impermeable plate, - wherein the first housing and the plate form a first space area in which the power electronics unit and a heating unit are arranged, - wherein the plate and the second housing form the fluid chamber with a second space area, - wherein the power electronics unit forms a DC-to-DC converter which converts a high voltage of 400 V to a low voltage of 12 V, wherein a heating power in the range of 3 kW to 4 kW, preferably 3.6 kW, is provided. - at least one power electronics unit being electrically connected to an electric power input and an electric power output, - at least one fluid chamber being fluidically connected to a fluid inlet and a fluid outlet, - wherein the fluid chamber and the power electronics unit are thermally coupled such that waste heat generated by the power electronics unit is used for heating a fluid flowing through the fluid chamber, - wherein the electric power converter device has a first operation mode and a second operation mode, - wherein the amount of waste heat generated by the power electronics unit is increased in the second operation mode compared to the first operation mode, characterized in that it comprises: - at least one heating unit being electrically connected to an electric power input and electric power output, - the fluid chamber and the heating unit being thermally coupled, - wherein the heating unit is used to heat a fluid flowing through the fluid chamber, - wherein electric power converter device comprises a first housing and a second housing, - wherein the first housing and the second housing are separated by a fluid-impermeable plate, - wherein the first housing and the plate form a first space area in which the power electronics unit and a heating unit are arranged, - wherein the plate and the second housing form the fluid chamber with a second space area, - wherein the power electronics unit forms a DC-to-DC converter which converts a high voltage of 400 V to a low voltage of 12 V, wherein a heating power in the range of 3 kW to 4 kW, preferably 3.6 kW, is provided. - at least one heating unit being electrically connected to an electric power input and electric power output, - the fluid chamber and the heating unit being thermally coupled, - wherein the heating unit is used to heat a fluid flowing through the fluid chamber, - wherein electric power converter device comprises a first housing and a second housing, - wherein the first housing and the second housing are separated by a fluid-impermeable plate, - wherein the first housing and the plate form a first space area in which the power electronics unit and a heating unit are arranged, - wherein the plate and the second housing form the fluid chamber with a second space area, - wherein the power electronics unit forms a DC-to-DC converter which converts a high voltage of 400 V to a low voltage of 12 V, wherein a heating power in the range of 3 kW to 4 kW, preferably 3.6 kW, is provided.