A method for controlling an internal combustion engine system

A method for controlling an internal combustion engine system comprising

• a combustor arranged to receive air and fuel, and combust the received air and fuel,
• an expander arranged to expand exhaust gases from the combustion in the combustor and to extract energy from the expanded exhaust gases,
• an exhaust guide arranged to guide exhaust gases from the combustor to the expander, and
• an expander inlet valve arranged to control a communication between the exhaust guide and the expander,
• the method comprising
• controlling the expander inlet valve so as to adjust the pressure in the exhaust guide, comprising
• determining the pressure in the exhaust guide, whereby the control of the expander inlet valve comprises controlling the expander inlet valve at least partly based on the determined pressure in the exhaust guide.

An internal combustion engine system comprising

• a combustor arranged to receive air and fuel, and combust the received air and fuel,
• an expander arranged to expand exhaust gases from the combustion in the combustor and to extract energy from the expanded exhaust gases,
• an exhaust guide arranged to guide exhaust gases from the combustor to the expander, and
• an expander inlet valve arranged to control a communication between the exhaust guide and the expander,
• wherein the engine system comprises pressure determining means arranged to determine the pressure in the exhaust guide, the expander inlet valve being arranged so as to present a variable and controllable opening sequence.