Abstract: A method for controlling the power available on the electric traction chain of a powertrain (GMP) consisting of a heat engine that can transmit the torque from same to the wheels at different transmission ratios, a first electric machine (ME), a second electric machine (HSG) linked alternately to the input shafts of the heat engine or of the first electric machine (ME) in the powertrain (GMP), and a battery supplying power to the electric machines, characterised in that the supply voltage of the electric machines is established by a DC/DC voltage converter (13) arranged between the terminals of the battery and those of the electric machines, capable of imposing on them a voltage equal to that of the battery (Ubat), or indeed a voltage (Udc) higher than same.