Supercharged internal combustion engine with exhaust-gas turbocharging arrangement, and method for operating an internal combustion engine of said type

A supercharged internal combustion engine system, comprising:

• an intake system for supply of charge air to an internal combustion engine;
• an exhaust-gas discharge system for discharge of exhaust gases from the internal combustion engine;
• at least two series-connected exhaust-gas turbochargers which each comprise a turbine arranged in the exhaust-gas discharge system and a compressor arranged in the intake system, the at least two series-connected exhaust-gas turbochargers including a first exhaust-gas turbocharger that serves as a low-pressure stage and a second exhaust-gas turbocharger that serves as a high-pressure stage, a second compressor of the second exhaust-gas turbocharger arranged downstream of a first compressor of the first exhaust-gas turbocharger, a first turbine of the first exhaust-gas turbocharger arranged downstream of a second turbine of the second exhaust-gas turbocharger;
• a third bypass line in which a third valve is arranged;
• a third turbine arranged in the exhaust-gas discharge system in parallel with respect to the second turbine of the second exhaust-gas turbocharger, the third turbine equipped with a variable turbine geometry and connected in terms of drive to a generator;
• a fourth valve for activation purposes arranged upstream of the third turbine,
• a first bypass line in which a first valve is arranged and which branches off from the exhaust-gas discharge system upstream of the third turbine and the second turbine of the second exhaust-gas turbocharger and which opens into the exhaust-gas discharge system again downstream of the third turbine and the second turbine;
• a third compressor arranged in the intake system between the first compressor of the first exhaust-gas turbocharger and the second compressor of the second exhaust-gas turbocharger and which is connected in terms of drive to an electric motor;
• and
• a second bypass line in which a second valve is arranged and which branches off from the intake system between the first compressor of the first exhaust-gas turbocharger and the third compressor and which opens into the intake system between the third compressor and the second compressor of the second exhaust-gas turbocharger.