METHOD OF CONTROLLING A HYBRID PROPULSION SYSTEM OF A VEHICLE

A method of controlling a hybrid propulsion system of a vehicle, is described. The propulsion system includes an in-series arrangement including an internal combustion engine (E), a first clutch (K0), an electric motor (M), a second clutch (K1) and a gearbox (G) having an input shaft and an output shaft connected to the drive wheels of the vehicle. The first clutch (K0) is arranged between the internal combustion engine (E) and the electric motor (M), and the second clutch (K1) is arranged between the electric motor (M) and said input shaft of the gearbox (G). The method includes a first operating mode of starting the internal combustion engine (E) by means of the electric motor (M), a second operating mode of actuating a gear shift, and a third operating mode which actuates in parallel a start of the internal combustion engine (E) and a gear shift. The method includes passing from the first operating mode to the third operating mode even if the start of the internal combustion engine (E) has not been yet completed, or passing from the second operating mode to the third operating mode even if the actuation of the gear shift has not been yet completed, so that the transition from one operating mode to another can be freely actuated at any time, depending upon the operating conditions of the hybrid propulsion system.