The present invention is relative to a engine apparatus comprising a combustion engine, a low pressure compressor connected to a high pressure turbine. The apparatus also comprises a low pressure turbine and a high pressure compressor. The engine apparatus according to the invention comprises an electrical torque converter comprising at least an electric generator connected so as to be driven by said low pressure turbine and a first electric motor connected so as to drive said high pressure compressor. The torque converter also comprises electronic conversion means suitable to convert the electric energy produce by said electric generator and to power supply and control at least said first electric motor.