Method for controlling an engine apparatus, said apparatus comprising at least: - an internal combustion engine having an air intake line and a gases exhaust line; - at least a first compressor arranged on said air intake line; - a high pressure turbine arranged on said exhaust line, said high pressure turbine being mechanically connected with said first compressor; - a power turbine arranged downstream to said high pressure turbine according to the flow direction of the exhaust gases; - an asynchronous machine operatively connected to said power turbine, wherein said method comprises the steps of: A1) detecting the real value of the rotational speed of said high pressure turbine by first speed detecting means and detecting the real value of the rotational speed of said low pressure turbine by second speed detecting means; A2) comparing the real value of said rotational speed of said high pressure turbine with a first speed reference value (RSHPT*) and comparing said real value of said rotational speed of said power turbine with a second speed reference value (RSLPT*); A3) if said real value of said high pressure turbine is higher than a first speed reference value (RSHPT*), then increasing the rotational speed (RSLPT) of said power turbine, by means of said asynchronous machine, by keeping its value below a second reference value (RSLPT*) and until said real value of the rotational speed of said high pressure turbine is less or equal of said first speed reference value (RSHPT*). - an internal combustion engine having an air intake line and a gases exhaust line; - at least a first compressor arranged on said air intake line; - a high pressure turbine arranged on said exhaust line, said high pressure turbine being mechanically connected with said first compressor; - a power turbine arranged downstream to said high pressure turbine according to the flow direction of the exhaust gases; - an asynchronous machine operatively connected to said power turbine, wherein said method comprises the steps of: A1) detecting the real value of the rotational speed of said high pressure turbine by first speed detecting means and detecting the real value of the rotational speed of said low pressure turbine by second speed detecting means; A2) comparing the real value of said rotational speed of said high pressure turbine with a first speed reference value (RSHPT*) and comparing said real value of said rotational speed of said power turbine with a second speed reference value (RSLPT*); A3) if said real value of said high pressure turbine is higher than a first speed reference value (RSHPT*), then increasing the rotational speed (RSLPT) of said power turbine, by means of said asynchronous machine, by keeping its value below a second reference value (RSLPT*) and until said real value of the rotational speed of said high pressure turbine is less or equal of said first speed reference value (RSHPT*). A1) detecting the real value of the rotational speed of said high pressure turbine by first speed detecting means and detecting the real value of the rotational speed of said low pressure turbine by second speed detecting means; A2) comparing the real value of said rotational speed of said high pressure turbine with a first speed reference value (RSHPT*) and comparing said real value of said rotational speed of said power turbine with a second speed reference value (RSLPT*); A3) if said real value of said high pressure turbine is higher than a first speed reference value (RSHPT*), then increasing the rotational speed (RSLPT) of said power turbine, by means of said asynchronous machine, by keeping its value below a second reference value (RSLPT*) and until said real value of the rotational speed of said high pressure turbine is less or equal of said first speed reference value (RSHPT*).