A system and method are for managing the energy supplied to a transport vehicle. A first and a second source of energy provide electrical energy to power at least one piece of consumer equipment of the vehicle. An intermediate energy transmission system receives electrical energy provided by at least one of the two sources of energy and transfers it to the at least one piece of consumer equipment. An energy conversion-control system applies, at the input of the intermediate energy transmission system, the electrical energy to be provided, adjusted depending on the operational state of the first source of energy and on an input signal indicative of an operational state of the second source. The first source of energy includes an internal combustion engine connected to a permanent-magnet alternator that is placed between the internal combustion engine and the energy conversion-control system.